Filter insert and filter having a filter bypass valve, the filter including the filter insert

ABSTRACT

An exchangeable filter insert that separates an unfiltered side and a filtered side of a filter, the filter having a filter housing, an inlet for liquid to be filtered and an outlet for filtered liquid. A filter bypass valve has a valve seat and a valve body guided so as to be movable relative to the valve seat and preloaded in the closing direction. The valve seat is fixed to the filter. The valve body is guided in the filter so as to be fixed to the filter. A spring that preloads the valve body in the closing direction is guided in the filter so as to be fixed to the filter. The filter insert has a spring prestresser support that, in the state in which the insert is placed into the filter housing, supports and pre-stresses the spring at its end facing away from the valve body.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.14/917,902, filed Mar. 9, 2016, which is a 371 of PCT/EP2014/002400filed Sep. 6, 2014 and which claims the benefit of the U.S. ProvisionalApplication No. 61/875,834, filed on Sep. 10, 2013, U.S. ProvisionalApplication No. 61/975,121, filed on Apr. 4, 2014, and the priority ofthe German patent application No. 202014104029.3 filed on Aug. 28, 2014,the entire disclosures of which are incorporated herein by way ofreference.

BACKGROUND OF THE INVENTION

The present invention relates to a filter having a filter housing havingan inlet for liquid to be filtered and having an outlet for filteredliquid, having an exchangeable filter insert that separates anunfiltered side and a filtered side of the filter from one another, andhaving a filter bypass valve that is made up of a valve seat and a valvebody that is guided so as to be movable relative to the valve seat andis preloaded in the closing direction. Moreover, the present inventionrelates to a filter insert that works together with the above-namedfilter.

A first filter of the type named above is known from U.S. Pat. No.6,579,448 B2. This document discloses a filter having an exchangeablefilter insert and having a filter bypass valve. A valve seat of thefilter bypass valve is situated on the filter insert, specifically onits upper end plate. A valve body, a spring that preloads the valve bodyin the closing direction, and a spring support are fashioned so as to befixed to the housing. Specifically, the spring support is provided on acentral pipe socket or supporting element fixed to the housing.

Another filter is known from U.S. Pat. No. 6,685,829 B1. This documentdiscloses a filter having an exchangeable filter insert and having afilter bypass valve. A valve seat is provided on the filter insert, herespecifically on its lower end plate. A valve body, a spring thatpreloads the valve body in the closing direction, and a spring supportare here realized so as to be fixed to the housing. The valve body isfashioned on a central pipe socket that is fixed to the housing but iscapable of displacement in an axially limited manner. The spring issituated as a pressure spring between the pipe socket and the housing.

DE 10 2009 021 973 A1 discloses a further filter having an exchangeablefilter insert and having a filter bypass valve. The valve seat, thevalve body, the spring, and a first spring support of the filter bypassvalve are here parts of the filter insert. On a central pipe socketfixed to the filter, a second spring support is provided that, when thefilter insert is placed onto the pipe socket during installation of thefilter insert in the filter housing, takes over the supporting of thespring and increases its prestressing.

From U.S. Pat. No. 8,123,937 B2, additional filters are known having anexchangeable filter insert and having a filter bypass valve. The valveseat and the valve body of the filter bypass valve are here eachprovided on the filter insert, specifically on its upper end plate. Apressure spring that preloads the valve body in the closing direction,and an additional actuating element that, when the filter insert is inplace, transmits the spring force to the valve body, are configured soas to be fixed to the housing, specifically in a central supportingelement fixed to the housing.

WO2006/112 853 A1 also discloses a filter having an exchangeable filterinsert and having a filter bypass valve. Here, the valve seat isprovided on the filter insert, specifically on its upper end plate. Avalve body, a spring that preloads the valve body in the closingdirection, and a spring support are realized so as to be fixed to thehousing. Specifically, the valve body and the spring are guided in anupper end region of a central supporting element that is fixed to thehousing. The spring support is also fashioned on the supporting element.

In filters of the type described above, in which the valve seat on theexchangeable filter insert and the valve body are realized so as to befixed to the filter, after each change of filter insert there is a valvemating with interacting valve components that is not checked beforehandfor tightness and is also not capable of being checked ahead of time fortightness. In practice, this results relatively frequently in filterbypass valves that are not tight in their closing position, throughwhich, undesirably, there is a constant flow of liquid that isunfiltered and that impairs the purity necessary for the actuallyintended use of the filtered liquid. The solutions known from theexisting art as indicated in the three last-named documents above, inwhich in addition to the valve seat the valve body is also provided onthe exchangeable filter insert, require an additional actuating element,and in part even an additional spring, which disadvantageously increasesthe number of components and thus the production and assembly costs.Also, in this way the filter inserts require significantly more outlayfor their construction, and are therefore more expensive, which hasnoticeable effects every time the filter insert is exchanged. Finally,the known filters have the disadvantage that the opening pressure of thefilter bypass valve can be modified only with a relatively high outlay.

SUMMARY OF THE INVENTION

An object of the present invention is therefore to provide a filter ofthe type named above that avoids the disadvantages of the existing artand that in particular ensures a good and long-lasting tightness of thefilter bypass valve in its closing position, requiring as few componentsas possible for its functioning and capable of being manufactured at lowcost, and with which it is possible to modify the opening pressure ofthe filter bypass valve with a low technical outlay. Moreover, an objectof the present invention includes the provision of a filter insert thatworks together with the filter, the filter insert also having for itspart as simple a design as possible and being capable of beingmanufactured at low cost, and with which the filter can be operatedreliably and with a high degree of effectiveness.

The solution of the first part of the object, relating to the filter, isachieved according to the present invention with a filter of the typenamed above that is characterized in that the valve seat is situated inthe filter so as to be fixed to the filter, that the valve body isguided in the filter so as to be fixed to the filter, that a spring thatpreloads the valve body in the closing direction is guided in the filterso as to be fixed to the filter, and that the filter insert has a springsupport that, when the filter insert is in place in the filter housing,supports and prestresses the spring at its end facing away from thevalve body.

The present invention advantageously achieves the effect that theimmediately interacting valve parts can be checked for tightness duringthe manufacture of the filter, because the valve seat and the valve bodyof the filter bypass valve are both components fixed to the filter, andthese valve parts are therefore already present in the filter when thefilter insert is not in place. It is additionally advantageous that thevalve seat and the valve body of the filter bypass valve always remainin the filter when its filter insert is changed, thereby excludingunchecked and possibly untight valve matings.

A significant further advantage is that it requires only a low outlay tomodify the opening pressure of the filter bypass valve, by simplymodifying the filter insert with regard to the position or length of thespring support that supports and prestresses the springs. In this way,the springs can be more or less strongly prestressed during installationof the filter insert, which permits a problem-free setting of thedesired opening pressure of the filter bypass valve, even during arunning series production.

It is also advantageous that the filter bypass valve makes do with onlyone spring, and, besides the valve body, requires no additional movableactuating elements. Apart from the spring support, the filter insertdoes not have to accommodate or have any additional parts of the filterbypass valve, so that, as a consumable part, the filter insert remainstechnically simple and low-cost.

An advantageous embodiment of the filter provides that the filterhousing has in its interior a central pipe socket, that the valve seatis fashioned on or attached to the pipe socket, and that the valve bodyand the spring are guided on the pipe socket. In this embodiment of thefilter, the central pipe socket is used for an integrated housing of thefilter bypass valve, which advantageously avoids additional requiredconstructive space.

The present invention further proposes that the valve seat is formed byan annular body that is axially fixed on the outer circumference of thepipe socket, and is tightly situated thereon, having at least onethrough-opening running in its axial direction. In this way, theinterior of the pipe socket remains free for the flowing through offiltered liquid.

So that on the one hand an adequately large flow cross-section can beprovided for the bypassing of the filter as needed, and on the otherhand the annular body can be fashioned so as to be adequately andpermanently stable, it is proposed that a plurality of through-openingsare made in the annular body, situated at a distance from one another inthe circumferential direction thereof.

Preferably, for reasons related to flow and production, thethrough-openings are made so as to have a cross-section that is round oris shaped as a segment of a ring.

For the reliable and long-lasting ensuring of the desired tightness ofthe filter bypass valve in its closed position, it is provided that thevalve seat formed by the annular body is made of an elastomericmaterial, or is provided with an elastomeric coating at least on its endface forming the valve seat, or that the valve body is made of anelastomeric material, or is provided with an elastomeric coating atleast on its side facing the valve seat.

Corresponding to the above-described realization of the valve seat, thevalve body is usefully formed by an annular valve body that is guided onthe outer circumference of the pipe socket and is axially displaceable.In this way, the valve body is guided so as to be displaceable in theaxial direction in a technically simple yet reliable fashion, and inthis way can move between its closing position, situated on the valveseat, and an open position at a distance from the valve seat.

In order to avoid losses of tightness of the filter bypass valve in itsclosing position that may possibly occur over the time of use of thefilter due to a relative rotation of the valve body and the valve seat,a further embodiment of the present invention provides that a guide thatguides the valve body on the outer circumference of the pipe socket inaxially displaceable fashion forms a lock against a rotation of thevalve body in the circumferential direction relative to the pipe socket.Such a lock can for example be realized in a technically simple mannerthrough one or more grooves running in the axial direction on one of thetwo components, and one or more ribs running therein on the other of thetwo components.

In order to ensure a tilt-free and clamping-free guiding of the valvebody on the pipe socket, a secure sealing of the filter bypass valve inits closing position, and a reliable and precise seating of the valve onthe valve body, it is preferably provided that the valve body is madeL-shaped in cross-section, having a longer limb of the L running in theaxial direction and a shorter limb of the L running in the radialdirection pointing outward or inward, an end face, facing the valveseat, of the shorter L limb forming a surface of the valve body thatworks together with the valve seat, an end face, facing away from thevalve seat, of the shorter L limb forming a seating surface and theouter circumference or inner circumference of the longer L limb forminga centering surface for the spring, and the inner circumference of thevalve body forming a guide surface for guiding the valve body on theouter circumference of the pipe socket.

The spring support for the spring that preloads the valve body of thefilter bypass valve in the closing direction is, according to thepresent invention, provided on the filter insert, and, in a concretedevelopment, the spring support is preferably formed by a, or on a,supporting element that forms a part of the filter insert, or by an, oron an, end plate of the filter insert. Thus, for the spring support,elements that are already present on or in the filter insert are used,which avoids an additional component outlay.

In order to realize the interaction of the spring and spring support inas secure and reliable a fashion as possible, the present inventionproposes that between the free end of the spring support and the end ofthe spring facing this free end there is situated an intermediate ringthat is guided in axially displaceable fashion on the outercircumference of the pipe socket, such that when the filter insert is inplace the spring abuts the side of the intermediate ring facing awayfrom the spring support and the spring support abuts the side of theintermediate ring facing away from the spring. Advantageously, theintermediate ring can be realized and shaped differently at its twoaxial sides, and in particular so as to be adapted optimally to thespring on the one side and to the spring support on the other side.

So that the spring, in its provided position, is held securely even whenno filter insert is situated in the filter, a stop is usefully situatedon the side of the spring facing away from the valve body, on the pipesocket, such that when the filter insert is in place in the filterhousing the end of the spring remote from the valve body has an axialdistance from the stop, and when the filter insert is removed from thefilter housing the end of the spring remote from the valve body abutsthe stop immediately or indirectly.

A first development relating to this provides that the stop is formed bya stop collar situated fixedly on the pipe socket in the axial andcircumferential direction, having a collar part that protrudes radiallyoutward having one or more open intermediate spaces distributed aroundits circumference.

An alternative embodiment provides that the stop is formed by stoptongues situated fixedly on the pipe socket, or made in one piecetherewith, in the axial and circumferential direction, each having aradially outward-protruding stop tab, open intermediate spaces existingbetween each two stop tabs over the circumference of the pipe socket.

In order to prevent installation of unsuitable foreign filter inserts inthe filter according to the present invention, it is proposed that thespring support has one or more support arms that are shaped andconfigured corresponding to the shape and configuration of the openintermediate spaces, and that, when the filter insert is placed into thefilter housing, run through the open intermediate spaces and form akey-lock coding with the stop. This achieves the effect that only thosefilter inserts can be placed into the filter that have the fittingcoding, in the form of a particular shape and configuration of the arms.Foreign filter inserts that do not have the required coding eithercannot be put in place, because they collide with the collar part, orcannot support the springs, because they do not have the spring support.

In addition, it is proposed that the stop has, on its side facing awayfrom the spring, between each two adjacent intermediate spaces, arespective individual introductory bevel, or two roof-shapedintroductory bevels, by which, during installation of the filter insert,the support arms situated thereon of the spring support canautomatically be guided into the intermediate spaces. In this way, it isensured that a mutual finding of support arms and intermediate spacestakes place even without particular attention or operating steps on thepart of the installation or maintenance personnel.

In a particularly advantageous embodiment, the filter according to thepresent invention is realized as a screw-on exchangeable filter, an endface of the filter being fashioned as a connecting flange for connectingthe filter to a coupling flange of a device having a circuit for liquidto be filtered, such as an internal combustion engine of a motorvehicle, and an end region of the pipe socket having, in the region ofthe connecting flange, a screw threading that can be screwed togetherwith a counter-threading in or on the coupling flange. In thisembodiment, the filter according to the present invention can be used asa replacement for a conventional screw-on filter cartridge that is onlyexchangeable as a whole, without having to make any modifications oradaptations at the side of the coupling flange. As determined by thecoupling flange, the connecting flange of the filter is shaped so as tofit, for example with a central pipe socket protruding axially from thefilter housing. For a coupling flange, as is also known in practice,having an outwardly protruding threaded connector, the filter accordingto the present invention can of course also be realized having a centralpipe socket that is flush with the plane of the connecting flange or isrecessed relative thereto.

For example, the screw threading on the end region of the pipe socket isan external threading, and the counter-threading is an inner threadingin the coupling flange.

Alternatively, the screw threading on the end region of the pipe socketcan be an inner threading, and the counter-threading can be an externalthreading on a threaded nipple situated on the coupling flange.

At the filter, the pipe socket can be connected fixedly andnon-detachably to the filter housing, and the filter housing can, inparticular for the purpose of filter maintenance, be capable of beingunscrewed from the coupling flange together with the pipe socket as aunit.

Alternatively, the pipe socket can be screwed to the filter housing indetachable fashion, and, after a first screwing of the filter onto thecoupling flange, the pipe socket can remain permanently connected to thecoupling flange, so that subsequently the filter housing can be screwedoff from the coupling flange without the pipe socket.

In an embodiment of the filter, the pipe socket is made in one part orin one piece.

Alternatively, the pipe socket can be formed from two pipe socketsegments that can be detachably connected to one another, in particularscrewed together.

For the two-part realization of the pipe socket, it is preferablyfurther provided that a first, flange-side pipe socket segment has orbears the valve seat, the valve body, and the spring, and, after a firstscrewing of the filter onto the coupling flange, remains permanentlyconnected thereto, and that a second pipe socket segment remote from theflange is connected fixedly and non-detachably to the filter housing.

In order to prevent the filter from running empty when there is astandstill of the liquid circuit, it is proposed that the first pipesocket segment at the flange side has or bears a return check valvecovering the inlet of the filter.

Here, in a further embodiment, the return check valve can have aflexible valve membrane and a rigid membrane bearer, each surroundingthe flange-side pipe socket segment, and the membrane bearer can befashioned in one piece with the first pipe socket segment, or can beconnected thereto in positionally fixed fashion, preferably locked.Alternatively, the membrane bearer can be a flange-type expansion of thevalve seat, i.e., a part of the filter bypass valve. In this way, ineach of the named embodiments a space-saving housing and technicallysimple integration of the return check valve is achieved.

In addition, when the filter insert is in place in the filter the valvemembrane is usefully clamped at its radially inner edge region againstthe membrane bearer by the filter insert, in particular by a sealingring situated radially inwardly thereon. In this way, particular holdingmeans for the valve membrane are advantageously not required.

Many filters of the type considered here have a screw cover as a part ofa filter housing, or have a screw-on housing. For safe operation thatdoes not damage the environment, it is essential that the screw cover orthe screw-on housing not become detached automatically during operationof the filter. For filters according to the present invention in whichthe filter housing is fashioned as a screw-on housing or has a screwcover, it is therefore provided that the filter is provided with ananti-rotational lock, an anti-rotational lock ring being guided inaxially displaceable fashion in the filter housing on the pipe socket,such that when the filter insert is in place in the filter housing, thespring presses the anti-rotation lock ring, with its end face facingaway from the spring, against a counter-surface of the filter housing orof the screw-on housing or screw cover. In this way, an additional veryadvantageous use of the spring is achieved, because the spring not onlypreloads the valve body of the filter bypass valve in its closingdirection, but now additionally also loads an anti-rotational lock ringwith a force required for its securing effect.

In order not to have to install a separate component in the filter forthe anti-rotation lock ring, the anti-rotation lock ring is preferablyconnected to a supporting element forming a part of the filter insert,or is made in one piece therewith.

A development of the filter provides that the end face, facing away fromthe spring, of the anti-rotation lock ring and the counter-surface ofthe filter housing each have a contour that varies in its axial height,regarded in the circumferential direction, and that interlock. This hasthe effect that when the filter housing or screw cover or screwed-onhousing is unscrewed, a certain specifiable resistance has to beovercome in order to rotate the interlocking contours relative to oneanother. By choosing a sufficiently high resistance that still howeverpermits an intentional unscrewing, an undesired automatic unscrewing isprevented.

In addition, here it is preferably provided that an upward inclinerunning in the unscrewing direction is steeper than a downward inclinerunning in the screw-on direction of the interacting contours. In thisway, advantageously the torque that has to be applied for loosening isgreater than the torque required for tightening. Here, the degree ofthis difference can be influenced and determined by the differencebetween the mentioned upward incline and the mentioned downward incline.The interacting contours can for example be realized so as to bewave-shaped, or as a sequence of bevels, also with flat segmentssituated between them.

Because the spring support that prestresses the spring of the filterbypass valve is a part of the filter insert, it has to be ensured thatduring operation of the filter the filter insert assumes a definedposition in the filter housing, seen in the axial direction, becauseotherwise an incorrect prestressing of the spring, and thus a wrongopening pressure of the filter bypass valve, would occur. Therefore, inthis regard the present invention proposes that the filter housing has,in its circumferential wall, an inner diameter step against which thefilter insert can abut with its flange-side end plate during itsintroduction into the filter housing, for axial positioning.

Filters of the type considered here as a rule require maintenance,because the useful life of the filter insert is limited, and the inserthas to be replaced from time to time. In order to ensure that, duringeach filter maintenance including a change of filter insert, the sealthat seals the filter against the coupling flange is also replaced, itis preferably provided that a sealing ring bearer is radially outwardlyconnected or made in one piece with a flange-side end plate of thefilter insert, on which there is attached, or there can be attached, asealing ring that seals the filter against the coupling flange of thedevice having a circuit having liquid to be filtered.

So that, when the filter is attached on the coupling flange, the sealingring can move into its sealing position without being forced, it isprovided that the sealing ring bearer has a cylindrical outercircumferential surface on which the sealing ring is attached or can beattached in an axially floating fashion.

A first configuration which is advantageous functionally and from thepoint of view of manufacturing results if the filter bypass valve issituated at the height of a first axial end of the filter insert.

A second configuration which is advantageous functionally and from thepoint of view of manufacturing results if the filter bypass valve issituated at the height of a second axial end of the filter insert.

Particularly preferably, the filter bypass valve is situated in theregion of the end of the filter insert that is the upper end duringoperation of the filter, because there the least possible amount ofdisturbing deposition of dirt particles on the parts of the filterbypass valve is to be expected.

In a further preferred embodiment of the filter according to the presentinvention, it is provided that it is realized as a screw-on exchangeablefilter, the filter being fashioned for connection with a coupling flangeof a device having a circuit having liquid to be filtered, the filterhaving a flange-side base plate having a screw threading that can bescrewed together with a counter-threading in or on the coupling flange,and the filter bypass valve being situated in a valve holder that formsa part of the base plate or is connected to the base plate. In thisembodiment as well, a compact construction and advantageousmanufacturability are achieved.

In a further embodiment, here it is provided that the filter housing isrealized as a screw housing having a screw threading on its flange-sideend region, by which the filter housing can be screwed onto a screwthreading situated radially outwardly on the base plate.

It is further proposed that after a first assembly of the filter on thecoupling flange the filter housing can be unscrewed from the base platetogether with the filter insert for filter maintenance, and that thebase plate with the valve holder and the filter bypass valve on thecoupling flange are remaining parts of the filter. During filtermaintenance, only the filter insert is replaced, while the filter bypassvalve is fixed to the filter, i.e., is a part of the filter that ispermanent over the lifespan of the filter.

A development provides that the valve holder is made closed at itscircumference, and has on its end face remote from the flange at leastone stop for the spring in its state relieved of stress by the springsupport of the filter insert, and at least one passage for filteredliquid. In this way, the spring is secured against loss, and at the sametime permits a flow of filtered liquid through the valve holder.

In order to prevent a disturbing or damaging entrance of dirt particlesinto the outlet for filtered liquid during filter maintenance withexchange of the filter insert, it is proposed that there be situatedbetween the spring and the passage a covering element loaded by thespring in the direction toward the passage, such that in the assembledstate of the filter the spring support situated on the filter insertsupports the spring via the covering element, and the covering elementclosing the passage when the filter insert is removed.

In order to prevent an emptying of the filter when the liquid circuit isat a standstill in the filter embodiments having a base plate as well,at least one eccentric through-opening forming the inlet of the filteris usefully made in the base plate, and on the side of the base plateremote from the flange there is situated a return check valve thatcovers the inlet, the return check valve having a circular valvemembrane that covers the inlet and that is clamped, at its radiallyinner edge region, between the base plate and the valve holder connectedto the base plate. In addition, here, advantageously, no particularfastening and holding means for the valve membrane are required.

So that the filter can be manufactured at low cost in large piece countsand has as low a weight as possible, preferably both the base plate andthe filter housing of the filter are parts made of plastic. Usefully,these parts are manufactured as specifically shaped injection-moldedparts requiring no further cutting processing. Alternatively, the baseplate and/or the filter housing can also be parts made of metal, e.g.,shaped plate parts made of steel plate, or die-cast parts, preferablymade of light metal.

In order to make it possible to prestress the spring of the filterbypass valve reliably and in a technically simple manner, it ispreferably provided that the spring support is formed by a plurality ofsupport arms connected to a central supporting element of the filterinsert or made in one piece therewith, extending into the valve holderwhen the filter insert is in place in the filter. Alternatively, thespring support can also be made in annular fashion in order to provideas large a contact surface as possible to the spring of the filterbypass valve.

For the purpose of the greatest possible prevention of the use ofunsuitable or lower-quality foreign filter inserts in the filteraccording to the present invention, the present invention proposes thatthe valve holder has, for each support arm, an introduction opening thatis matched in its position and shape, and that the support arms and theintroduction openings form with one another a key-lock coding thatallows installation only of the filter insert having support armspositioned and shaped with the correct fit to the introduction openings.The support arms and the associated introduction openings can have thesame design as one another. Alternatively, the support arms can be madedifferently from one another and the associated introduction openingscan correspondingly also be made different from one another in order toachieve a key-lock coding that presents a still greater obstacle to theuse of foreign filter inserts.

In order to protect the support arms of the spring support from forcesthat occur during the positioning of the support arms relative to theintroduction openings and that could cause damage, the present inventionproposes that in addition to the support arms forming the spring supportthe filter insert has first positioning elements, that the valve holderhas second positioning elements in addition to the introductionopenings, and that, when placed into the filter, the filter insert canbe guided by the first and second positioning elements into a positionin the circumferential direction that is ready for engagement of itssupport arms relative to the introduction openings of the valve holder.

According to a development in this regard, the positioning elements arepreferably formed by at least one introductory bevel, having asubsequent axial introduction groove on the one hand, and at least oneintroduction projection or axial introduction rib on the other hand.

In order to make it possible to manufacture the valve holderadvantageously with regard to technology and cost, and to secure theparts housed therein of the filter bypass valve in the valve holder, itis provided that the valve holder is fashioned in two parts, having afirst holder part connected to the base plate and having the valve seat,and having a second holder part connected to the first holder part andsituated remote from the valve seat. The first holder part is preferablyconnected fixedly to the base plate, e.g., by welding. The holder partsare preferably locked to one another, because such a locking connectionrequires little outlay during manufacture, and can easily be producedduring assembly.

For the above-described embodiment of the filter, it is also preferablyprovided that the counter-threading in or on the coupling flange issituated as an outer threading on a threaded nipple that protrudes fromthe plane of the coupling flange and forms a part of the couplingflange.

In a different embodiment of the filter, it is provided that it isrealized as a screw-on exchangeable filter, the filter being fashionedfor connection to a coupling flange of a device having a circuit havingliquid to be filtered, the filter housing having at the flange side ascrew threading that can be screwed together with a counter-threading inor on the coupling flange, the filter bypass valve being situated in avalve holder having a hollow cylindrical end piece at the flange side,and the end piece being capable of being pressed into a filtered liquidchannel of the coupling flange before or during a first assembly of thefilter on the coupling flange. In this way, a very simple and rapidconnection of the valve holder containing the filter bypass valve to thecoupling flange is achieved, the valve holder remaining permanently onthe coupling flange after this connection is produced. Only the filterhousing can be screwed off from the coupling flange, together with thefilter insert situated therein which here as well has the spring supportfor prestressing the spring of the filter bypass valve.

So that when the filter is open, i.e., the filter housing isdisassembled and the filter insert is removed, the spring of the filterbypass valve cannot be lost, but at the same time filtered liquid canflow through the valve holder, it is provided that the valve holder ismade closed at the circumference and has on its end face remote from theflange at least one stop for the spring, in its state in which it is notloaded by the spring support of the filter insert, and has at least onepassage for filtered liquid.

In order, in this embodiment of the filter as well, to prevent dirtparticles from falling into the outlet for filtered liquid when thefilter insert is exchanged, a covering element, loaded by the spring inthe direction toward the passage, is usefully situated between thespring and the passage, such that in the assembled state of the filterthe spring support situated on the filter insert supports the spring viathe covering element, and such that the covering element closes thepassage when the filter insert is removed. When the filter insert is inplace in the filter, its spring support holds the covering element in aposition removed from the passage, so that a flow of liquid through thepassage to the outlet of the filter is then enabled.

In order to achieve the second part of the object, a filter insert thatworks together with the filter of the type described above is proposedthat is characterized in that it has a spring support, and that when thefilter insert is in place in the filter housing the spring of the filterbypass valve can be supported and can be prestressed, at its end facingaway from the valve body, by the spring support of the filter insert.

With such a filter insert, the filter according to the present inventioncan be operated in a manner corresponding to its purpose and with theadvantages explained above, such that, by means of the spring support onthe filter insert, the spring of the filter bypass valve in the filtercan be prestressed, and thus, by means of corresponding realization ofthe filter insert, the desired opening pressure of the filter bypassvalve can be defined without having to modify or exchange other parts ofthe filter for this purpose.

On the filter insert, the spring support is preferably fashioned by a,or on a, supporting element that forms a part of the filter insert. As arule, the filter insert already has a supporting element that supportsthe filter material body during operation of the filter againstcollapsing as a result of pressure differences between its two sides.Thus, here the supporting element is beneficially additionally used forthe integration of the spring support.

Alternatively, the spring support can be formed by an end plate of thefilter insert, or can be provided on an end plate of the filter insert.

The filter insert can advantageously be manufactured in variousembodiments, in particular having different axial length or position ofits spring support, whereby a prestressing of the spring, and thus theopening pressure of the filter bypass valve of the filter equipped withthe filter insert, can be set to a desired value. It is particularlyadvantageous that, as needed, the opening pressure of the filter bypassvalve can also still be modified later by exchanging the filter insertfor one having a different spring support length or spring supportposition, without having to make any modifications to the filter itself.

In order to prevent an installation of foreign filter inserts in thefilter according to the present invention, for the filter insert it isfurther proposed according to the present invention that the springsupport has a plurality of support arms that are shaped and configuredcorresponding to the shape and configuration of the open intermediatespaces in the stop or of the introduction openings in the valve holderof the associated filter, such that when the filter insert is placedinto the filter housing the support arms can be guided through the openintermediate spaces or introduction openings, and the support armsforming a key-lock coding with the open intermediate spaces or with theintroduction openings. In this way, only one particular matched filterinsert can be put in place in a particular filter, which prevents theuse of non-fitting, and often qualitatively lower-value, foreign filterinserts.

Finally, for the filter insert according to the present invention it isproposed that it has, in addition to the support arms forming the springsupport, first positioning elements, and that by means of the firstpositioning elements and by means of second positioning elementscooperating therewith and provided on the valve holder in addition tothe introduction openings, when the filter insert is placed into thefilter it can be guided into a position in the circumferential directionof its support arms ready for engagement relative to the introductionopenings of the valve holder. In this way, the support arms can be maderelatively delicate, because they have to exert only axial forces on thespring or on the covering element. In contrast, the support arms arecompletely relieved of the stress of forces acting in thecircumferential direction, such as those that occur during thepositioning of the filter insert relative to the filter bypass valve orto its valve holder, because these forces are accepted only by thepositioning elements. The support arms on the one hand and thepositioning elements on the other hand can therefore each be optimallycontoured and dimensioned for their respective purpose, which promotesdurability and operational reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, exemplary embodiments of the present invention areexplained on the basis of a drawing.

FIG. 1 shows a first filter having an exchangeable filter insert andhaving a filter bypass valve, in an angled longitudinal section,

FIG. 2 shows the filter of FIG. 1 in a top view, with the sectional lineI-I for FIG. 1.

FIG. 3 shows the filter of FIG. 1 in cross-section according to thesectional line III-III in FIG. 1,

FIG. 4 shows an enlarged detail of the filter of FIG. 1 with the filterbypass valve in the closed position,

FIG. 5 shows the same detail as FIG. 4, here with the filter bypassvalve in the open position.

FIG. 6 shows the filter of FIG. 1 without filter insert, in longitudinalsection,

FIG. 7 shows the filter in a second embodiment, in the delivered state,in longitudinal section,

FIG. 8 shows the filter of FIG. 7 in the installed state, with closedfilter bypass valve, in longitudinal section,

FIG. 9 shows the filter of FIG. 8 without filter insert, in longitudinalsection,

FIG. 10 shows the filter of FIGS. 8 and 9 with removed filter housingand removed filter insert, in longitudinal section,

FIG. 11 shows the filter insert of the filter according to FIGS. 7 and 8as an individual part, in longitudinal section,

FIG. 12 shows the filter housing of the filter of FIGS. 7 through 9, inlongitudinal section,

FIG. 13 shows the filter of FIG. 8, here with open filter bypass valve,in longitudinal section,

FIG. 14 shows the filter of FIG. 7 in cross-section according to thesectional line XIV-XIV in FIG. 7,

FIG. 15 shows a valve seat of the filter according to FIGS. 7 through14, in a first embodiment, in a top view,

FIG. 16 shows the valve seat of the filter according to FIGS. 7 through14, in a second embodiment, in a top view,

FIG. 17 shows die filter in a third embodiment, in the installed statewith closed filter bypass valve and with an anti-rotation lock, inlongitudinal section,

FIG. 18 shows the filter of FIG. 17 in cross-section according to thesectional line B-B in FIG. 17,

FIG. 19 shows the filter of FIG. 17 in cross-section according to thesectional line C-C in FIG. 17,

FIG. 20 shows the filter of FIGS. 17 through 19 in longitudinal sectionaccording to the sectional line D-D in FIG. 19,

FIG. 21 shows the filter of FIGS. 17 through 20 in longitudinal sectionaccording to the sectional line E-E in FIG. 20,

FIG. 22 shows the filter of FIGS. 17 through 21 in longitudinal sectionaccording to the sectional line F-F in FIG. 20,

FIG. 23 shows a central pipe socket as a part of the filter according toFIG. 17 through 22, as an individual part, in an oblique view fromabove,

FIG. 24 shows a supporting element as a part of the filter according toFIG. 17 through 22, as an individual part, in an oblique view fromabove,

FIG. 25 shows a filter housing as a part of the filter according to FIG.17 through 22, as an individual part, in an oblique view from below,

FIG. 26 shows a constructive unit of the filter housing according toFIG. 25 and of the pipe socket according to FIG. 23, in an oblique viewfrom below,

FIG. 27 shows an enlarged detail from FIG. 21 with the anti-rotationlock in a first embodiment,

FIG. 28 shows the detail of FIG. 21 with the anti-rotation lock in asecond embodiment,

FIG. 29 shows the filter in a fourth embodiment, in the installed statewith closed filter bypass valve and with a first filter insert shown intwo different embodiments in the left and right halves of the Figure, inlongitudinal section,

FIG. 30 shows the filter in an embodiment modified relative to FIG. 29,in the installed state with closed filter bypass valve and with a secondfilter insert shown in two different embodiments in the left and righthalves of the Figure, in longitudinal section,

FIG. 31 shows the filter in a further embodiment modified relative toFIG. 29, in the installed state with closed filter bypass valve, andwith a third filter insert shown in two different embodiments in theleft and right halves of the Figure, in longitudinal section,

FIG. 32 shows a valve body and a modified embodiment, in longitudinalsection.

FIG. 33 shows a valve seat in a modified embodiment, in longitudinalsection,

FIG. 34 shows a filter in a further embodiment, in longitudinal section,

FIG. 35 shows the filter of FIG. 17 in a modified embodiment, having ananti-rotation lock for the valve body of the filter bypass valve, inlongitudinal section,

FIG. 36 shows the filter of FIG. 35 in cross-section according to thesectional line H-H in FIG. 35,

FIG. 37 shows the detail circled in FIG. 36 in an enlargedrepresentation,

FIG. 38 shows the filter in a further embodiment, in longitudinalsection,

FIG. 39 shows the filter of FIG. 38 in cross-section according to thesectional line G-G in FIG. 38,

FIG. 40 shows the filter of FIG. 38 in cross-section according to thesectional line H-H in FIG. 38,

FIG. 41 shows the filter housing and the filter insert of the filtersituated therein of FIG. 38, in longitudinal section,

FIG. 42 shows the filter housing having the filter insert of FIG. 41, inan oblique view from below,

FIG. 43 shows the filter insert of the filter of FIG. 38 in an obliqueview from below,

FIG. 44 shows the filter insert of FIG. 43 in longitudinal section,

FIG. 45 shows the filter insert of FIG. 44 in cross-section according tothe sectional line F′-F′ in FIG. 44,

FIG. 46 shows the filter housing of the filter of FIG. 38 in an obliqueview from below,

FIG. 47 shows a coupling flange of the filter with filter partsremaining thereon after removal of filter housing and filter insert,

FIG. 48 shows the subject matter of FIG. 47 in longitudinal section,

FIG. 49 shows detail Y of FIG. 39 in an enlarged representation,

FIG. 50 shows detail X of FIG. 40 in an enlarged representation,

FIG. 51 shows a constructive unit including a filter bypass valve and areturn check valve as parts of the filter of FIG. 38, in an oblique viewfrom below,

FIG. 52 shows the constructive unit of FIG. 51 together with a couplingflange and a filter housing with filter insert, in an exploded view,obliquely from below,

FIG. 53 shows detail Z of FIG. 48 in an enlarged representation,

FIG. 54 shows detail W of FIG. 38 in an enlarged representation,

FIG. 55 shows the filter insert of the filter in a modified embodimentfor a filter without return check valve, in an oblique view from below,

FIG. 56 shows the filter insert of FIG. 55 in longitudinal section,

FIG. 57 shows the filter in a further embodiment in longitudinalsection,

FIG. 58 shows a constructive unit with filter bypass valve as a part ofthe filter of FIG. 57, in a front view,

FIG. 59 shows the constructive unit of FIG. 58 in a state assembled to acoupling flange, in an oblique view from above,

FIG. 60 shows the filter housing with filter insert of the filtersituated therein of FIG. 57, in an oblique view from below,

FIG. 61 shows the filter housing with filter insert of FIG. 60, inlongitudinal section,

FIG. 62 shows the constructive unit of FIG. 58 together with a couplingflange and a filter housing with filter insert situated therein, in anexploded view,

FIG. 63 shows the subject matter of FIG. 59 in longitudinal section,

FIG. 64 shows the filter in a further embodiment, in longitudinalsection,

FIG. 65 shows the filter in a further embodiment, in longitudinalsection,

FIG. 66 shows the filter in a further embodiment, in longitudinalsection,

FIG. 67 shows the filter in a further embodiment, in longitudinalsection,

FIG. 68 shows the filter of FIG. 67 in cross-section according to thesectional line B-B in FIG. 67,

FIG. 69 shows detail V of FIG. 68 in an enlarged representation,

FIG. 70 shows the filter of FIG. 67 in a cross-section according to thesectional line D-D in FIG. 67,

FIG. 71 shows detail U of FIG. 70 in an enlarged representation,

FIG. 72 shows the filter of FIG. 67 in longitudinal section according tothe sectional line C-C in FIG. 68,

FIG. 73 shows detail X in FIG. 72 in an enlarged representation,

FIG. 74 shows the filter of FIG. 72 in cross-section according to thesectional line I-I in FIG. 72,

FIG. 75 shows detail W in FIG. 74 in an enlarged representation,

FIG. 76 shows the filter in a further embodiment, in longitudinalsection,

FIG. 77 shows detail Y of FIG. 76, in an enlarged representation,

FIG. 78 shows the filter according to FIG. 76 without filter housing,with filter insert shown only partly, in a first phase of the assemblyon the coupling flange, in a front view, partially in longitudinalsection,

FIG. 79 shows the filter of FIG. 78 in the same representation, in asecond phase of the assembly on the coupling flange,

FIG. 80 shows the filter of FIG. 78 in the same representation, in athird phase of the assembly on the coupling flange,

FIG. 81 shows the filter of FIG. 78 in the same representation, in afourth phase of the assembly on the coupling flange,

FIG. 82 shows the coupling flange together with a constructive unit,including a filter bypass valve and a return check valve, of the filterof FIG. 76, after the removal of filter housing and filter insert, in afront view,

FIG. 83 shows the constructive unit of FIG. 82, without spring andwithout covering element of the return check valve, in a longitudinallysectioned view,

FIG. 84 shows the complete constructive unit of FIG. 82 in longitudinalsection,

FIG. 85 shows the filter housing and the filter insert situated therein,in a longitudinally sectioned view,

FIG. 86 shows a filter bypass valve in a modified embodiment, togetherwith the coupling flange, in longitudinal section,

FIG. 87 shows the filter in a further embodiment, in longitudinalsection,

FIG. 88 shows a constructive unit, including a filter bypass valve and areturn check valve, of the filter of FIG. 87, in the state connected toa coupling flange, in an oblique view from above,

FIG. 89 shows the filter in a further embodiment, in longitudinalsection,

FIG. 90 shows the filter of FIG. 89 in a state with filter housing andfilter insert removed from the coupling flange, in longitudinal section,

FIG. 91 shows the filter in a further embodiment, in a state in place ona coupling flange, in longitudinal section, and

FIG. 92 shows the filter of FIG. 91 in a state disassembled from thecoupling flange, in longitudinal section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description of the Figures, identical parts in thevarious Figures of the drawing have always been provided with the samereference characters, so that not every reference character has to beexplained again in every Figure.

FIG. 1 of the drawing shows an exemplary embodiment of a filter 1,realized as a screw-on exchangeable filter, and shown here inlongitudinal section. Filter 1 has an essentially cup-shaped filterhousing 2 having a circumferential wall 20, having an open end face 21,here pointing downward, and a closed end face 22, here pointing upward.In the center of upper end face 22 a tool mount projection 23, such as ahexagon, is integrally formed, on which a screw tool can be placed.

Through the interior of filter 1 there runs a central pipe socket 4whose outer, here lower, end region 40 protrudes from filter housing 2in the axial direction, and is provided there with an outer screwthreading 40′. On its inner, here upper, end region 41, pipe socket 4abuts the underside of upper end face 22 of filter housing 2. Here, inthe depicted exemplary embodiment pipe socket 4 is fixedly connected tofilter housing 2, for example by welding along a weld seam 25′. For thispurpose, filter housing 2 and pipe socket 4 are for example made ofsteel plate. In its region situated inside filter housing 2, pipe socket4 has a plurality of perforations 42 distributed in the circumferentialand longitudinal direction.

In addition, in filter housing 2 of filter 1 there is situated anexchangeable filter insert 3 that is made up of a hollow cylindricalfilter material body 30 and two end plates 31 and 32 enclosing said bodyat the ends. Each end plate 31, 32 has a central perforation 31′. 32′,so that filter insert 3 can be placed onto pipe socket 4 from below, andin this way can be introduced into the interior of filter housing 2.Moreover, on the inner circumference of filter material body 30 there issituated an inner grid-type support body 37 for the radial supporting offilter material body 30 when liquid to be filtered flows through it inthe radial direction from the outside to the inside.

In addition, filter 1 has an integrated filter bypass valve 5, whichhere is situated at the height of upper end plate 32 of filter insert 3.Filter bypass valve 5 has a valve seat 50 that is fashioned as anannular element, and is attached tightly on the outer circumference ofinner and region 41 of pipe socket 4. A plurality of axialthrough-openings 50′, of which only one is visible in FIG. 1, runthrough valve seat 50 fashioned as annular element.

A likewise annular valve body 51 works together with valve seat 50, saidvalve body being guided in axially displaceable fashion underneath valveseat 50, on the outer circumference of pipe socket 4. Valve body 51 ispreloaded in the direction toward valve seat 50, and thus in the closingdirection of filter bypass valve 5, by a spring 52 realized as a helicalpressure spring. At its end oriented away from valve body 51, spring 52is supported by filter insert 3. For this purpose, filter insert 3 has,in the depicted exemplary embodiment, a spring support 53 that here hasthe form of four protruding support arms 53′ that run upward in theaxial direction and that are fashioned in one piece with innersupporting element 37. This spring support 53 supports spring 52 at itslower end via an intermediate ring 54 that is guided in axiallydisplaceable fashion on the outer circumference of pipe socket 4.

The force with which spring 52 acts on valve body 51 in the closingdirection is thus determined, inter alia, by spring support 53, herespecifically by its axial length or axial position. This offers theadvantageous possibility of easily modifying the opening pressure offilter bypass valve 5, by installing into filter 1 a filter insert 3having a correspondingly modified spring support 53. A larger axiallength of spring support 53 results in a higher prestressing of spring52, and thus to a higher opening pressure of filter bypass valve 5.Conversely, a shorter axial length of spring support 53 results in areduced prestressing of spring 52, and thus to a lower opening pressureof filter bypass valve 5.

Finally, on the outer circumference of pipe socket 4, underneath spring52, a stop 43 is also situated in axially non-displaceable fashion, andso as to be incapable of rotation in the circumferential direction, thestop here being formed by a sheet metal part and for example pressedonto pipe socket 4. Distributed around its circumference, stop 43 has aplurality of openings or open intermediate spaces (not visible inFIG. 1) 44, through each of which there runs a respective support arm53′ of spring support 53. Here, intermediate spaces 44 and support arms53′ of spring support 53 form with one another a key-lock coding thatpermits only the placement of a fitting filter insert 3, matched to thecoding, into filter 1.

Filter insert 3 separates an unfiltered side 13 of filter 1, situatedoutside filter insert 3, from a filtered side 14 of filter 1, situatedin the interior of filter insert 3 and of pipe socket 4. For the sealingof filter insert 3 against pipe socket 4 onto which filter insert 3 isplaced, filter insert 3 has on its lower end plate 31 a sealing lip 35that radially outwardly encloses perforation 31′, and likewise has onits upper end plate 32 a sealing lip 36 that radially outward enclosesperforation 32′.

Lower end face 21 of filter 1 is fashioned as connecting flange 10,which can be brought into a detachable connection with a coupling flangeon a device having a circuit having liquid such as lubricant oil that isto be filtered, such as an internal combustion engine, using threading40′ of pipe socket 4. Radially external to outer end region 40 of pipesocket 4 there is situated an inlet 11 through which the liquid to befiltered can flow from below to above into unfiltered side 13 of filter1. The interior of pipe socket 4 forms an outlet 12 for filtered liquid.

In order to seal the flange connection between filter 1 and theassociated device not shown in FIG. 1, such as an internal combustionengine, a sealing ring 39 is used that is situated on lower end face 21of filter 1. Here, sealing ring 39 is held by a sealing ring bearer 34that is situated circumferentially radially inward from sealing ring 39.Here, sealing ring bearer 34 is made in one piece with lower end plate31 of filter insert 3, and is connected to end plate 31 via connectingwebs 33 that are situated at distances from one another, seen in thecircumferential direction. Inlet 11 for liquid to be filtered runsthrough the intermediate spaces between connecting webs 33.

In normal operation of filter 1, the liquid to be cleaned, such aslubricant oil of an internal combustion engine, runs through inlet 11fashioned on lower end face 21 to unfiltered side 13 of filter 1, andfrom there runs through filter material body 30 to filtered side 14 offilter 1, situated radially inwardly from the filter material body. Fromthere, the filtered liquid moves through perforations 42 in pipe socket4 into its interior, and flows out downward through the interior,through outlet 12. Here, filter bypass valve is in its closed position,as shown in FIG. 1.

The spatial orientation of filter 1 does not play a role in itsoperation; filter 1 can be used in any spatial position. The orientationshown in the drawing is given only as an example. Preferably, however,the filter realization according to FIG. 1 is a standing configurationin which filter bypass valve 5 is situated at the top in the filter. Inthis way, a deposition of dirt particles on the parts of filter bypassvalve 5, which could possibly disturb the functioning, is avoided to thegreatest possible extent. In this way, dirt particles that havepreviously settled in the lowest region of the filter on its unfilteredside 13 are also prevented from being carried along to filtered side 14when filter bypass valve 5 is open.

If an impermissibly high pressure difference, above a specifiableboundary value, occurs between unfiltered side 13 and filtered side 14of filter 1, this has the result that the liquid at unfiltered side 13acts, through through-openings 50′, on valve body 51 so strongly thatthe valve body is moved away from valve seat 50, against the force ofspring 52, thus opening filter bypass valve 5. In this state, a flowpath for the liquid is released that bypasses filter material body 30,going from unfiltered side 13 through through-openings 50′ to filteredside 14, and through perforations 42 into the interior of pipe socket 4,i.e., to outlet 12 of filter 1. If the pressure difference decreasesbelow the boundary value, the force of spring 52 again predominates, andfilter bypass valve 5 closes.

FIG. 2 of the drawing shows filter 1 of FIG. 1 in a top view, andsectional line I-I of the longitudinal section shown in FIG. 1 is alsoshown in FIG. 2. Visible here is only filter housing 2. Facing theviewer is the upper end face 22, remote from the flange, of filterhousing 2 having central tool attachment projection 23. Circumferentialwall 20 of filter housing 2 runs circumferentially.

In FIG. 3, filter 1 of FIG. 1 is shown in cross-section. Circumferentialwall 20 of filter housing 2 runs radially externally. In the interior ofhousing 2 there is situated filter insert 3 with filter material body30, formed by a filter material strand arranged in folds. Underneathfilter material body 30 is situated lower end plate 31 of filter insert3, to which plate sealing ring bearer 34 is connected in one piece viaconnecting webs 33.

Radially inwardly from filter material body 30, inner supporting element37 is situated, having spring support 53 in the form of the four supportarms 53′ running in the axial direction. Between support arms 53′ ofspring support 53, stop 43 is visible, with the open intermediate spaces44 provided therein for support arms 53′ of spring support 53. Theradially innermost part is formed by central pipe socket 4, at whoselower inner end outlet 12 is situated.

FIGS. 4 and 5 show an enlarged detail of filter 1 with filter bypassvalve 5 according to FIG. 1, shown in FIG. 4 in the closed position andin FIG. 5 in the open position.

At the top in FIGS. 4 and 5, a part of upper end face 22 of filterhousing 2 having tool attachment projection 23 can be seen. Central pipesocket 4 is welded, with its inner end region 41, to the underside ofend face 22, and runs downward from there.

In the left part of FIGS. 4 and 5, a small part of filter insert 3 canbe seen having filter material body 30 and upper end plate 32 with itssealing lip 36, which abuts outer circumference of valve seat 50 insealing fashion and here separates unfiltered side 13 from filtered side14 of filter 1.

Valve seat 50, having the shape of an annular element, is fixedly andtightly attached on the outer circumference of inner end region 41 ofpipe socket 4. Through-openings 50′ run through valve seat 50 in theaxial direction.

Axially underneath valve seat 50 is situated valve body 51, alsorealized in the form of an annular element, guided displaceably in theaxial direction on the outer circumference of pipe socket 4. Valve body51 is preloaded with a force acting in the closing direction by spring52, situated underneath valve body 51. As long as the pressuredifference between unfiltered side 13 and filtered side 14 does notexceed a specifiable boundary value, spring 52 holds valve body 51 inliquid-tight seating on valve seat 50, and a flow of liquid fromunfiltered side 13 to filtered side 14 is possible only by flowingthrough filter material body 30 of filter insert 3.

FIG. 5 shows the open state of filter bypass valve 5, which occurs whenthe pressure difference between unfiltered side 13 and filtered side 14exceeds the specified boundary value. In this case, the force exerted inthe opening direction through through-openings 50′ on valve body 51 bythe liquid situated at unfiltered side 13 is greater than the forceexerted in the closing direction on valve body 51 by spring 52. Valvebody 51 is now removed from valve seat 50 through displacement downwardin the axial direction, thus releasing a flow path for the liquid fromunfiltered side 13 to filtered side 14 through through-openings 50′ andperforations 42 of central pipe socket 4, bypassing filter material body30. In this way, impermissibly large pressure differences betweenunfiltered side 13 and filtered side 14 can be avoided, which occur forexample when the liquid to be filtered is viscous as a result of lowtemperature, and/or when filter material body 30 is clogged with dirtparticles.

FIG. 6 shows filter 1 in a state with filter insert 3 removed, again inlongitudinal section as in FIG. 1. The outer cladding of filter 1 formsfilter housing 2 with its circumferential wall 20 and its closed upperend face 22 on which tool attachment projection 23 is integrally formed.

In the interior of housing 2 there is situated central pipe socket 4,which is connected with its upper end region 41 fixedly and tightly tothe underside of upper end face 22 of filter housing 2.

All parts of filter bypass valve 5, with the exception of spring support53, which forms a part of filter insert 3, are situated on central pipesocket 4. At the very top on pipe socket 4, annular valve seat 50,having through-openings 50′, is externally seated in positionally fixedand liquid-tight fashion. Under it is situated axially displaceablevalve body 51, also annular in shape, which here is seated in sealingposition on the underside of valve seat 50 and seals through-openings50′. Valve body 51 is brought into this closing position by spring 52,whose lower end abuts axially displaceable intermediate ring 54. Here,because intermediate ring 54 is now not loaded by spring support 53 offilter insert 3, intermediate ring 54 is supported on stop 43, which isattached non-displaceably and non-rotatably on the outer circumferenceof pipe socket 4, for example pushed on with a press fit. In this way,all axially displaceable parts of filter bypass valve 5, namely valvebody 51, spring 52, and intermediate ring 54, are held captive on pipesocket 4.

In order to install filter insert 3 into filter 1, according to FIG. 6filter insert 3 is pushed into filter housing 2 from the open end face21. By rotating filter insert 3 in the circumferential direction,support arms 53′ of spring support 53 are brought into coincidence withopen intermediate spaces 44 of stop 43, so that support arms 53′ thenpass through intermediate spaces 44, and, upon further pushing in offilter insert 3, move into abutment on intermediate ring 54. Filter 1completed in this way can then be screwed, with its connecting flange10, onto a coupling flange of an associated device. Here, during thescrewing on filter insert 3 is pressed still further into filter housing2, thereby simultaneously tensioning spring 52. At the end of thisscrew-on process, sealing ring 39 seals the flange connection, andspring 52 has reached its target prestressing.

FIG. 7 shows filter 1 in a second embodiment, in the delivered state, inlongitudinal section. Filter 1 here as well has a cup-shaped filterhousing 2 having a circumferential wall 20 having an open (here lower)end face 21 and a closed (here upper) end face 22 in whose center a toolattachment projection 23 is integrally formed. A threaded connector 25,situated concentric to circumferential wall 20 and protruding into theinterior of filter housing 2, is fixedly connected to upper end face 22of filter housing 2, here welded by a weld seam 25′. For this purpose,filter housing 2 and threaded connector 25 are made of steel plate,housing 2 preferably being a deep-drawn part.

In addition, a central pipe socket 4 is situated concentric tocircumferential wall 20 in the interior of filter housing 2, the pipesocket being provided in its inner (here upper) end region 41 with anouter threading 41′ by which pipe socket 4 is screwed into threadedconnector 25.

In its outer (here lower) end region 40, pipe socket 4 has an outerthreading 40′ by which filter 1 can be screwed onto a coupling flange ofan associated device (not shown here) such as an internal combustionengine of a motor vehicle. In its region between outer end region 40 andinner end region 41, pipe socket 4 has a plurality of perforations 42distributed in the circumferential and axial direction. Moreover, pipesocket 4 here has three stops 43, distributed approximately in itslongitudinal center around its circumference. Here, each stop 43 isformed by a stop tongue 43.2 pressed in one piece from the material ofpipe socket 4, having a stop tab 43.3 pointing outward in the radialdirection.

A filter insert 3 is pushed from below onto the outer circumference ofpipe socket 4 and threaded connector 25. Filter insert 3 is made up of ahollow cylindrical filter material body that is enclosed at the ends bya lower end plate 31 and an upper end plate 32. Each end plate 31, 32has a central perforation 31′, 32′, each having an associated sealinglip 35, 36. A grid-type supporting element 37 is situated radiallyinwardly from filter material body 30.

A sealing ring bearer 34 is connected in one piece to lower end plate 31via connecting webs 33, the bearer bearing a circumferential sealingring 39. In the unloaded state, sealing ring 39 protrudes outwardly,here downward, in the axial direction, past lower end face 21 of filterhousing 2, and, in the assembled state of filter 1, seals the filteragainst an associated coupling flange.

Finally, filter 1 according to FIG. 7 includes another filter bypassvalve 5 that here is situated in the lower region of filter housing 2 atthe height of lower end plate 31 of filter insert 3 on pipe socket 4. Avalve seat 50 is formed by an annular body situated tightly on pipesocket 4, having through-openings 50′ adjacent to one another in thecircumferential direction and running in the axial direction. In theassembled state of filter 1, valve seat 50 is fixed in the axialdirection and in the circumferential direction. An annular valve body 51that can be displaced on pipe socket 4 works together with valve seat50, the valve body being preloaded in the closing direction of filterbypass valve by a spring 52 in the form of a helical pressure spring 5.The end of spring 52 facing away from valve body 51 is supported by aspring support 53 that is fashioned on supporting element 37, moreprecisely on the lower end of its axial struts 38. In FIG. 7, filterbypass valve 5 is shown in its closing position. Here, valve body 51abuts valve seat 50 in sealing fashion, and seals through-openings 50′present therein.

The side of filter 1 pointing downward in FIG. 7 forms a connectingflange 10 for connecting filter 1 to an associated coupling flange.Radially outwardly from protruding lower end region 40 of central pipesocket 4, an inlet 11 for liquid that is to be cleaned such as lubricantoil runs into the interior of filter 1 at its unfiltered side 13.Radially inward from filter material body 30 there is situated afiltered region 14 of the filter that is connected via perforations 42to the interior of pipe socket 4, which forms a downward-leading outlet12 for filtered liquid.

In the state shown in FIG. 7, filter 1 can be supplied as apre-manufactured unit e.g., to an engine or vehicle manufacturer, whocan then quickly and easily install filter 1. Here, for this filterembodiment a suspended configuration is preferred in which filter bypassvalve 5 is then situated at the top in filter 1, in its cleanest region.In general, however, this filter 1 can also be used in any spatialposition.

FIG. 8 shows filter 1 of FIG. 7 in the installed state with closedfilter bypass valve 7, in longitudinal section. In the lower part ofFIG. 8, a part is shown of a device 6 such as crank housing 6 of aninternal combustion engine, having at the top a coupling flange 60 onwhich filter 1 is in place with its connecting flange 10. For thispurpose, using a screw tool placed on tool attachment projection 23filter 1 is screwed into lower end region 40, provided with threading40′, of pipe socket 4, into a counter-threading 61′ of coupling flange60, until lower end face 21 of filter housing 2 abuts the surface ofcoupling flange 60, or until a specifiable tightening torque is reached.Outwardly, the flange connection is sealed in liquid-tight fashion bythe now-compressed sealing ring 39; in the drawing, for reasons ofgraphic representation sealing ring 39 is shown only in its relaxed,non-compressed state. Valve seat 50 now abuts, with its lower end face,a stop 65 fashioned in coupling flange 60, defining and securing theaxial position of the valve seat 50.

In normal operation of this filter 1, liquid to be cleaned such aslubricant oil flows through an unfiltered liquid duct 62 in device 6 toinlet 11 of filter 1, and to its unfiltered side 13. The liquid thenflows through filter material body 30 of filter insert 3 in the radialdirection from the outside toward the inside, and moves to the filteredside 14 of filter 1, leaving behind dirt particles in filter materialbody 30. The filtered liquid flows downward through perforations 42,and, via outlet 12, into filtered liquid duct 61 of device 6.

In this normal state, in which a pressure difference between unfilteredside 13 and filtered side 14 remains below a specifiable boundary value,filter bypass valve 5 is closed, as shown in FIG. 8.

In its further parts, filter 1 in FIG. 8 corresponds to filter 1 in FIG.7, to whose description reference is made.

FIG. 9 shows filter 1 of FIG. 8 without filter insert 3, in longitudinalsection. Here, it is clear in particular that when filter insert 3 isnot present spring 52 is supported with its end remote from valve body51 on stop 43, specifically stop tab 43.3. In this way, it is ensuredthat spring 52 and valve body 51 are held captive on central pipe socket4 when no filter insert 3 is present.

For the placement of a filter insert 3 into filter 1, filter housing 2is removed, here by unscrewing from central pipe socket 4, as shown inFIG. 10, also in longitudinal section. For this purpose, the screwconnection of lower end region 40 of pipe socket 4 to outer threading40′ in threading 61′ of coupling flange 60 is realized with a largerunscrewing resistance than is the screw connection between threadedconnector 25 on filter housing 2 and threading 41′ on upper end region41 of pipe socket 4. Thus, when filter housing 2 is removed byunscrewing, pipe socket 4 remains connected to coupling flange 60. Thelarger unscrewing resistance of the screw connection between pipe socket4 and coupling flange 60 can for example be achieved in that this screwconnection is provided with a micro-encapsulated screw securing thatdeploys its securing effect when the screw connection is first produced.

When filter housing 2 is removed, here a filter insert 3 can be placedonto pipe socket 4 from above, and filter housing 2 can then be screwedon again. As soon as filter insert 3, together with filter housing 2,has been moved downward a certain distance on pipe socket 4, springsupport 53 on supporting element 37 of filter insert 3 (compare FIG. 8)comes into engagement with the upper end, facing away from valve body51, of spring 52, and prestresses this spring to a desired degree duringthe further movement downward. Thus, here as well filter insert 3provides the setting of a desired prestressing of spring 52, and thus adesired opening pressure of filter bypass valve 5.

FIG. 11 shows filter insert 3 of filter 1 according to FIGS. 7 and 8 asan individual part, in longitudinal section. Hollow cylindrical filtermaterial body 30 is tightly enclosed at its two ends by end plates 31and 32. Lower end plate 31 has central perforation 31′ havingcircumferential sealing lip 35. Moreover, sealing ring bearer 34, withsealing ring 39 held thereon, is connected in one piece to lower endplate 31 via connecting webs 33. Upper end plate 32 has a centralperforation 32′ that is surrounded by sealing lip 36.

Grid-type supporting element 37 is situated inside filter material body30, and this supporting element has a plurality of axial struts 38situated at a distance from one another in the circumferentialdirection. Here, its lower end forms spring support 53 for spring 52 offilter bypass valve 5.

During a filter maintenance, a used filter insert 3 is exchanged for afresh filter insert 3; all further parts of filter 1 continue to beused. Filter insert 3 is usefully made completely of combustiblematerials, so that consumed filter inserts can be easily and completelydisposed of thermally.

FIG. 12 shows filter housing 2 of filter 1 from FIGS. 7 through 9 as anindividual part in longitudinal section. Rotationally symmetrical hollowcylindrical circumferential wall 20 runs radially externally. Open endface 21 is situated at the bottom. At the top, closed end face 22 issituated, having tool attachment projection 23. Threaded connector 25,fixedly connected to the rest of filter housing 2 by weld seam 25′, issituated inside filter housing 2, concentric to circumferential wall 20.

FIG. 13 shows filter 1 of FIG. 8, here in an operating state with openfilter bypass valve 5, in longitudinal section. This operating stateoccurs when a pressure difference between unfiltered side 13 andfiltered side 14 of filter 1 exceeds a specifiable boundary value, forexample as a result of a high viscosity of the liquid at low temperatureand/or when filter material body 30 is clogged with dirt particles. Thishas the result that the force exerted in the opening direction on valvebody 51 by the liquid exceeds the force exerted on valve body 51 in theclosing direction by spring 52. In this case, the force of the liquidensures that valve body 51 is displaced, against the force of spring 52,in the axial direction on the outer circumference of pipe socket 4, andis lifted off from valve seat 50. In this way, an immediate flowconnection is released from unfiltered side 13 through through-openings50′ of valve seat 50 to filtered side 14, and through the interior ofpipe socket 4 to outlet 12 of filter 1, bypassing filter material body30.

With regard to the further parts shown in FIG. 13, reference is made tothe description of FIG. 8.

FIG. 14 shows filter 1 of FIG. 7 in cross-section along the sectionalline XIV-XIV in FIG. 7. Radially externally, circumferential wall 20 offilter housing 2 is visible. Radially inwardly, there follows sealingring bearer 34, which is connected to lower end plate 31 of filterinsert 3, situated in the background, by a plurality (here nine) ofconnecting webs 33 situated at a distance from one another in thecircumferential direction. Further radially inward there follows hollowcylindrical filter material body 30, formed by a filter material strandarranged in folds. Radially inward from filter material body 30 there issituated supporting element 37 with spring support 53 fashioned thereon.The radially innermost part is formed by central pipe socket 4 with itsstop 43 fashioned in one piece therewith and protruding radiallyoutward.

FIG. 15 shows a valve seat 50 of filter 1 according to FIGS. 7 through14 in a first embodiment, in a top view. Here it is particularly clearthat valve seat 50 has the form of an annular body. Through-openings 50′are here realized in the shape of annular segments in order to provideas large a through-flow cross-section as possible in the open state offilter bypass valve 5. Radially inward in valve seat 50, here an innerthreading 56 can be seen that includes only one thread pitch, which isused to screw valve seat 50 onto threading 40′ on outer end region 40 ofcentral pipe socket 4, as is shown for example in FIGS. 7 through 10 and13.

FIG. 16 shows valve seat 50 of filter 1 according to FIGS. 7 through 14in a second embodiment, in a top view. Here as well, valve seat 50 hasthe shape of an annular element, but here through-openings 50′ arerealized in the form of round openings closely adjacent to one another.Inner threading 56 is provided radially inwardly here as well.

FIG. 17 of the drawing shows Filter 1 in a third embodiment, in theinstalled state with closed filter bypass valve 5, and in additionhaving an anti-rotation lock 47, in longitudinal section. For reliablefunctioning of the liquid filter 1 having a screw-on housing, such asfilter housing 2 in filter 1 according to FIG. 17, it is essential foran automatic detachment by rotation to be reliably prevented. In theexample of filter 1 according to FIG. 17, this is achieved by anintegrated anti-rotation lock 47. Anti-rotation lock 47 is herefashioned between supporting element 37 of filter insert 3 on the onehand and threaded connector 25 on the inner side of filter housing 2 onthe other hand. Supporting element 37 cannot be rotated in thecircumferential direction relative to central pipe socket 4, or can beso rotated only to a very limited extent, but is made displaceable inthe axial direction. Because, as is also the case in the exemplaryembodiments described above, here spring support 53 fashioned onsupporting element 37 supports spring 52 of filter bypass valve 5 at itsend remote from valve body 51, spring 53 exerts a force acting in theaxial direction on axially movable supporting element 37 in thedirection toward threaded connector 25. In this way, an upper end faceof supporting body 37 and a lower end face of threaded connector 25 arepressed against one another with a force determined by the spring forceof spring 52. In addition, supporting element 37 and threaded connector25 are fashioned with interlocking contours on their surfaces thatcontact one another, as is further explained below. These contoursprovide the desired securing of filter housing 2, fashioned as a screwhousing, against undesirable automatic rotating loose from central pipesocket 4.

In this embodiment of filter 1 as well, central pipe socket 4 has in itscenter region on its circumference stop 43, here fashioned in the formof tabs that protrude outward in the radial direction fashioned in onepiece with pipe socket 4.

In the example according to FIG. 17, it is preferably provided thatfilter housing 2 is fashioned in one piece with threaded connector 25,and is an injection-molded part made of plastic. Preferably, it isfurther provided that central pipe socket 4 is here an injection-moldedpart made of plastic. A suitable plastic having the required mechanical,thermal, and chemical stability is for example polyamide (PA), which cancontain a certain portion of glass fibers.

As is also the case in the exemplary embodiments described above, thisexemplary embodiment of filter 1 according to FIG. 17 is equipped with afilter bypass valve 5. For this purpose, here as well valve seat 50 withits through-openings 50′ is screwed onto outer threading 40′ of lowerend region 40 of pipe socket 4. Valve element 51 is situated above valveseat 50 and here as well can be displaced in the axial direction onouter circumference of pipe socket 4. Spring 52 loads valve body 51 witha force acting in the closing direction.

With regard to the further parts in FIG. 17 and their functioning,reference is made to the above description, in particular of FIG. 8.

FIG. 18 shows filter 1 of FIG. 17 in cross-section along the sectionalline B-B in FIG. 17. Radially externally, filter housing 2 is visiblewith its circumferential wall 20. Radially inwardly therefrom, in thebackground there is situated lower end plate 31 with connecting webs 33for sealing ring bearer 34. Filter material body 30 is situated on lowerend plate 31 in the form of the folded filter material-strand. Grid-typesupporting element 37 is situated radially inward from filter materialbody 30. Here again, the radially innermost part of filter 1 is formedby central pipe socket 4, over whose outer circumference there protrudea total of four protruding tabs as stop 43. FIG. 18 illustrates thatsupporting element 37 and the tabs forming stop 43 overlap, seen in theradial direction, so that a rotation of supporting element relative tocentral pipe socket 4 is not possible, or is possible only to a verylimited extent.

FIG. 19 shows filter 1 of FIG. 17, also in cross-section, here accordingto sectional line C-C in FIG. 17. The radially outer part of filter 1,up to and including filter material body 30, corresponds to that of FIG.18, to whose description reference is made.

Radially inward from filter material body 30, here threaded connector 25of filter housing 2 is sectioned close to its lower end face, wherein atotal of eight recesses 28, regularly spaced from one another in thecircumferential direction, are formed as end-face contour. Conversely,on the end face, oriented toward threaded connector 25, of anti-rotationlock ring 47′, which forms a part of supporting element 37, cams 48 areintegrally formed in one piece, which enter into engagement withrecesses 28. Recesses 28 and cams 48 form together with spring 52anti-rotation lock 47. Because supporting element 37, as describedabove, is preloaded by spring 52 in the direction toward threadedconnector 25, recesses 28 and cams 48 form a kind of locking engagementthat prevents undesired automatic rotation of filter housing 2 againstsupporting element 37. Because for its part supporting element 37 issecured against rotation relative to pipe socket 4, filter housing 2cannot automatically rotate loose from central pipe socket 4, even whenthere are vibrations or pressure pulsations that occur during practicaloperation of filter 1.

FIG. 20 shows filter 1 of FIGS. 17 through 19 in longitudinal sectionaccording to sectional line D-D in FIG. 19. Underneath threadedconnector 25 of filter housing 2, supporting element 37 of filter insert3 is situated in axially displaceable fashion on the outer circumferenceof central pipe socket 4. The upward-oriented end face of supportingelement 37, and the downward-oriented end face of threaded connector 25,together form the above-described anti-rotation lock 47.

The downward-oriented end face of supporting element 37 here again formsspring support 53, which supports the end of spring 52 facing away fromvalve body 51. The tabs of stop 43 integrally formed in one piece oncentral pipe socket 4 provide, on the one hand, the desired rotationalsecuring of supporting element 37 relative to pipe socket 4, and on theother hand form the stop for spring 52 when no filter insert 3 ispresent in filter 1.

With regard to the further parts in FIG. 20 and their functioning,reference is made to the above description.

FIG. 21 shows filter 1 of FIGS. 17 through 20 in longitudinal sectionalong sectional line E-E in FIG. 20, anti-rotation lock 47 being hereparticularly illustrated. In the upper region of filter housing 2,threaded connector 25 is sectioned in its edge region. In the end faceof threaded connector 25, here one of the recesses 28 can be seen. Inrecess 28 there engages one of the cams 48, which is integrally formedon the upper end face of supporting element 37, here in continuation ofone of its axial struts 38.

With regard to the further details and FIG. 21, reference is made againto the above description.

FIG. 22 shows filter 1 of FIGS. 17 through 21, again in longitudinalsection, here according to sectional line F-F in FIG. 20. In thissection, central pipe socket 4, supporting element 37, valve seat 50,valve body 51, and spring 52 are visible in a side view. With its lowerend, spring 52 loads valve body 51 with a force acting in the closingdirection of filter bypass valve 5, i.e., with a force acting in thedirection toward valve seat 50.

With its upper end, the same spring 52 loads supporting element 37 witha force acting upward in the direction toward threaded connector 25. Theupper end of supporting element 37 is fashioned as anti-rotation lockring 47′ of anti-rotation lock 47. Cams 48 protrude past the upper sideof anti-rotation lock ring 47′, which cams here again stand inengagement with end-face recesses 28 of threaded connector 25, thustogether forming anti-rotation lock 47.

With regard to the further parts in FIG. 22, reference is made to thepreceding description.

FIG. 23 shows central pipe socket 4 as part of filter 1 according toFIGS. 17 through 22 as an individual part, in an oblique view fromabove. In its upper end region 41, pipe socket 4 has outer threading41′, and in its lower end region 40 outer threading 40′ is provided. Inthe region of pipe socket 4 situated between threadings 40′. 41′,perforations 42 are made therein.

At an axial distance from the lower end of upper threading 41′,distributed over the circumference the four tabs are integrally formedas stop 43, which protrude radially outward. In the axial direction,underneath each tab of stop 43 a rib-shaped longitudinal guide 49extends downward, each terminating at a distance from lower threading40′. Together with the tabs of stop 43, longitudinal guides 49 bringabout the locking of supporting element 37 against rotation relative topipe socket 4 when filter insert 3 is situated on pipe socket 4.Moreover, the tabs of stop 43 support spring 52 when filter insert 3 isremoved from filter 1, as described above.

FIG. 24 shows supporting element 37 as part of filter 1 according toFIGS. 17 through 22, as an individual part, in an oblique view fromabove. In particular, here it is clear that supporting element 37 hasthe shape of a hollow cylindrical annular grid that has a number ofaxial struts 38, as well as a respective annular strut above and below.Here, the upper annular strut forms the anti-rotation lock ring 47′ withcams 48 of anti-rotational lock 47. Supporting element 37 is preferablyan injection-molded part made of plastic.

FIG. 25 shows filter housing 2 as part of filter 1 according to FIG. 17through 22, as an individual part, in an oblique view from below, i.e.,in a view towards its open end face 21. The radially outer part offilter housing 2 is formed by its circumferential wall 20. Inside, inthe background, there is situated closed end face 22, from whichthreaded connector 25 protrudes into the interior of filter housing 2.The free end face, facing the observer, of threaded connector 25 isprovided with recesses 28 configured at regular spacings from oneanother in the circumferential direction.

FIG. 26 shows a constructive unit made up of filter housing 2 accordingto FIG. 25 and pipe socket 4 according to FIG. 23, in an oblique viewfrom below. In order to form this constructive unit, pipe socket 4 isscrewed into threaded connector 25 with its upper end region 41 andouter threading 41′ made there. On pipe socket 4, perforations 42, stop43, and longitudinal guides 49 are visible. Screw threading 40′ isattached on outer end region 40, facing the observer, of pipe socket 4.

FIG. 27 shows an enlarged detail of FIG. 21 with anti-rotation lock 47,in a first embodiment. At the top in FIG. 27, an edge region of threadedconnector 25, with one of recesses 28 in its end face, is visible. Underthis, a part can be seen of supporting element 37 with one of its axialstruts 38 and one of the cams 48. Here, recess 28 and cams 48 stand inengagement with one another, in order in this way to form anti-rotationlock 47. As described above, supporting element 37, movable in the axialdirection, is loaded by spring 52 (not visible here) with a forceoriented in the direction toward threaded connector 25. As FIG. 27illustrates, recess 28 here has, in both directions of rotation, i.e.,to the left and to the right in FIG. 27, symmetrical bevels each havingthe same upward incline or the same downward incline.

FIG. 28 shows the detail of FIG. 21 with anti-rotation lock 47 in asecond embodiment, for which it is characteristic that recess 28 in theend face of threaded connector 25 has, in the direction of rotation,i.e., to the left and to the right in FIG. 28, two different upward ordownward inclines, i.e., is asymmetrical. In FIG. 28, the upward inclineof recess 28 to the right is stronger than to the left. This bringsabout different rotational resistances depending on the direction ofrotation of filter housing 2 relative to supporting element 37, usefullyin such a way that in the tightening direction of rotation a lowerresistance of anti-rotation lock 47 is produced and in the looseningdirection of rotation a larger resistance thereof is produced.

FIG. 29 of the drawing shows filter 1 in the installed state with closedfilter bypass valve 5, in longitudinal section, two differentembodiments of a filter insert 3 fitting filter 1 according to FIG. 29being shown in the left and right half of FIG. 29. Here, in bothembodiments, supporting element 37 of filter insert 3 is situated as aseparate individual part on the inner circumference of filter materialbody 30, and is supported with its upper end against the lower side ofupper end face 32. As described above, the lower end of supportingelement 37 forms spring support 53 for spring 52 of filter bypass valve5.

The two filter inserts 3 in FIG. 29 differ in the position of the springsupport 53 fashioned thereon in each case; spring 52 is the same in bothhalves of the Figure. In the case of filter insert 3 shown in the lefthalf of FIG. 29, spring support 53 is situated at a greater axialdistance from valve body 51, while in the case of filter insert 3 shownin the right half of FIG. 29, its spring support 53 is situated at asmaller distance from valve body 51. Filter insert 3 in the left half ofFIG. 29 thus produces a lower prestressing of spring 52 than does filterinsert 3 in the right half of FIG. 29. In this way, correspondinglydifferent opening pressures of filter bypass valve 5 are also set. Inthis way it is therefore advantageously possible to set the openingpressure of filter bypass valve 5 to a desired value, or to easilymodify it as needed, solely by changing the position of spring support53 inside exchangeable filter insert 3, without having to modify anyother parts of filter 1.

With regard to the further parts in FIG. 29 and their function,reference is made to the above description, in particular of FIGS. 7 and8.

FIG. 30 shows filter 1 in an embodiment modified relative to that ofFIG. 29, again in the installed state with closed filter bypass valve 5and with a second filter insert 3 shown in two different embodiments inthe left and right halves of the Figure, in longitudinal section.

Differing from FIG. 29, in the example according to FIG. 30 supportingelement 37 of filter insert 3 is realized in one piece with upper endplate 32, so that here upper end plate 32, together with supportingelement 37 formed in one piece therewith, is used to set theprestressing of spring 52. Here as well, the different prestressing ofspring 52 takes place through different axial positioning of springsupport 53 on filter insert 3, as a comparison of the left and righthalves of FIG. 30 shows. Here as well, therefore, through simpleexchange of filter insert 3 with different axial positioning of springsupport 53, the opening pressure of filter bypass valve 5 can be set,and as needed can be set to a different value, without having to carryout modifications on the rest of filter 1.

FIG. 31 shows filter 1 in an embodiment further modified relative tothat of FIG. 29, again in the installed state with closed filter bypassvalve 5 and having a third filter insert 3 shown in two differentembodiments in the left and right halves of the Figure, in longitudinalsection. In this example it is essential that in each case filter insert3 is realized having a spring support 53 that is fashioned in one piecewith lower end plate 31. For this purpose, lower end plate 31 hasradially inwardly a hollow cylindrical projection that runs axiallyupward, ending in a collar that is oriented radially inward and thatforms spring support 53. In filter insert 3 shown in the left half ofFIG. 31, the projection running axially upward is fashioned with agreater length than in the case of filter insert 3 shown in the righthalf of FIG. 31, thereby producing two different prestressings of spring52, and thus also two different opening pressures of filter bypass valve5.

FIG. 32 shows, in longitudinal section, a valve body 51 in an embodimentmodified relative to the examples described above. Characteristic ofthis valve body 51 is that its end face that works together with valveseat 50 is provided with an elastomeric coating 57 in order to improvethe sealing effect in interaction with valve seat 50.

FIG. 33 shows a valve seat 50 in an embodiment modified relative to theabove-described examples, in longitudinal section. Characteristic forthis embodiment of valve seat 50 is that its end face that workstogether with valve body 51 is provided with an elastomeric coating 57,which likewise improves the sealing effect in interaction with valvebody 51.

Moreover, in the right part of FIG. 33 one of the through-openings 50′is visible, through which the liquid flow runs when filter bypass valve5 is open. Finally, on the inner circumference of annular valve seat 50,inner threading 56 situated there is visible, having a thread pitch withwhich valve seat 50 can be screwed onto threading 40′ on outer endregion 40 of central pipe socket 4.

Inside a filter 1, both valve seat 50 and valve body 51 can be providedwith elastomeric coating 57; alternatively, it can also suffice to equiponly valve seat 50 or only valve body 51 with elastomeric coating 57.

In the above-described exemplary embodiments of filter 1, this filter isa screw-on exchangeable filter having an exchangeable filter insert 3that can be attached on coupling flange 60 of the associated device 6,such as an internal combustion engine, instead of a screw-onexchangeable filter cartridge that can be exchanged only as a whole.Differing from this, FIG. 34 shows a filter 1 in an angled longitudinalsection, having a separate base 6′ with which it can be connected to anassociated device 6 such as an internal combustion engine or to afunctional module forming a part of the device. Moreover, filter 1according to FIG. 34 is a so-called suspended filter 1 in which a screwcover 20′, forming a detachable part of filter housing 2, can be screwedoff downward and removed. Correspondingly, here filter insert 3 is alsoput in place from below and taken off downwardly.

Here, the non-detachable part of filter housing 2 is realized in onepiece with base 6′, and is for example a pressure die-cast part made oflight metal such as aluminum. Screw cover 20′ can also be a pressuredie-cast part made of light metal, or alternatively can also be aninjection-molded part made of plastic. By means of a sealing ring 39,screw cover 20′, in its screwed-on state, seals against the rest offilter housing 2 in liquid-tight fashion. On its outer side, herepointing downward, screw cover 20′ has a tool attachment projection 23,for example a hexagon. Inside tool attachment projection 23, here astandard known screw valve is situated as a drain valve, in order tomake it possible to completely drain the interior of filter 1 of liquidbefore opening filter housing 2.

In the interior of filter housing 2, here as well there is situated afilter insert 3 that is made up of a hollow cylindrical filter materialbody 30 tightly enclosed at its two ends by end plates 31 and 32. In theinterior of filter material body 30, here as well there is situated agrid-type supporting element 37 whose basic shape is hollow andcylindrical. As is known, here filter insert 3 is detachably locked toscrew cover 20′ using locking arms situated on its lower end plate 31.

In addition, in the interior of filter housing 2 there is situated acentral pipe socket 4 that has in its upper end region 40 an externalscrew threading 40′ with which it is screwed into a counter-threading61′ in base 6′. With its end plate 32, which is at the top in FIG. 34and has a central perforation, filter insert 3 is placed from below ontocentral pipe socket 4.

A filter bypass valve 5 is situated on the outer circumference of pipesocket 4, at the height of upper end plate 32. For this purpose,immediately above upper end plate 32 an annular valve seat 50 isattached non-displaceably in the axial direction on the outercircumference of pipe socket 4, here by screwing on. Through-openings50′ run through valve seat 50, in its axial direction.

Immediately below valve seat 50 a valve body 51 is displaceably guidedin the axial direction on the outer circumference of pipe socket 4. Seenin longitudinal section, valve body 51 has the shape of an upside-downL, a longer L limb forming the guide on pipe socket 4, and a shorter Llimb protruding radially outward. An upper end face of the shorter Llimb works together with a lower end face of the valve seat 50; a lowerend face of the shorter L limb forms a seating surface for a spring 52that loads valve body 51 with a preloading force in the closingdirection.

The lower end of spring 52, facing away from valve body 51, is heresupported on a spring support 53, sectioned and visible at left in FIG.34, which is an integral and one-piece part of supporting element 37inside filter insert 3.

It can be seen that in this embodiment of filter 1 as well, theprestressing of spring 52, and thus the opening pressure of filterbypass valve 5, is determined and defined, or can be modified as needed,through the axial position of spring support 53 on filter insert 3.

During operation of filter 1 according to FIG. 34, a liquid to becleaned such as lubricant oil of an internal combustion engine flowsthrough an unfiltered liquid duct 62 in base 6′ to inlet 11 of filter 1,and to its unfiltered side 13. Flowing through filter material body 30of filter insert 3, the liquid moves to filtered side 14 of filter 1,leaving behind dirt particles, and flows through supporting element 37into central pipe socket 4, and flows through this socket to outlet 12,which goes into a filtered liquid duct 61 in base 6′.

As long as a pressure difference between unfiltered side 13 and filteredside 14 remains below a specifiable boundary value, filter bypass valve5 remains closed. If the pressure difference exceeds the specifiableboundary value, the force of the liquid acting through through-openings50′ on valve body 51 opens filter bypass valve 5, and a flow path isreleased from unfiltered side 13 through through-openings 50′ andperforations 42 in pipe socket 4, going immediately to filtered side 14,bypassing filter material body 30.

Here, valve body 51 is displaced against the force of spring 52 on theouter circumference of central pipe socket 4, in the axial directionthereof. For the purpose of establishing a good, tilt-free guiding ofvalve body 51 on central pipe socket 4, the axial length of valve body51 should usefully be at least as large as its inner diameter.

For the maintenance of filter 1 according to FIG. 34, the filter isfirst drained of fluid by opening the drain valve. Subsequently, screwcover 20′ is unscrewed, whereby simultaneously filter insert 3 lockedthereto is moved out from filter housing 2, moving downward, and ispulled off from central pipe socket 4. In this way, spring support 53,as part of filter insert 3, is also removed from the downward-pointingend of spring 52. To prevent spring 52 from falling out of filterhousing 2 and becoming lost, on the inner end (here pointing downward)of pipe socket 4, distributed around its circumference, a plurality ofradially outward-protruding tabs are integrally formed as stop 43, onwhich spring 52 abuts when filter insert 3 is removed. In this way,spring 52 and valve body 51 are secured in captive fashion on centralpipe socket 4.

During the manufacture and first installation of filter 1 according toFIG. 34, central pipe socket 4, with valve seat 50 and a valve body 51situated thereon, as well as spring 52, are screwed into threading 61′of filtered liquid duct 61, using threading 40′ on upper end region 40,and then remain there. During filter maintenance, only screw cover 20′then has to be unscrewed, and filter insert 3 is exchanged together withspring support 53 integrated therein.

As mentioned above, filter 1 is capable of operation in any spatialposition; thus, instead of as a suspended filter as in FIG. 34 filter 1can also be used as a lying or standing filter, or in any intermediateor oblique position. Here, filter bypass valve 5 is usefully situated ina position that during operation is situated as high up as possible, inorder to keep contamination of the valve seat 50 and valve body 51 bydirt particles deposited from the liquid as low as possible.

FIG. 35 of the drawing shows filter 1 of FIG. 17 in a modifiedembodiment, namely having a rotational securing for valve body 51 offilter bypass 5, in longitudinal section. Like the exemplary embodimentsdescribed above, this exemplary embodiment of filter 1 according to FIG.5 is also, equipped with a filter bypass valve 5. For this purpose, hereas well valve seat 50 with its through-openings 50′ is screwed ontoouter screw threading 40′ of lower end region 40 of pipe socket 4. Valvebody 51 is situated above valve seat 50, and here as well isdisplaceable in the axial direction on the outer circumference of pipesocket 4. Spring 52 loads valve body 51 with a force acting in theclosing direction.

Differing from the exemplary embodiment according to FIG. 17, in theexemplary embodiment according to FIG. 35 valve body 51 is securedagainst rotation relative to pipe socket 4 and relative to valve seat50. For this purpose, on the outer circumference of pipe socket 4, onits side pointing to the right in FIG. 35, there is situated aprotruding longitudinal rib 45 that runs in the longitudinal directionof pipe socket 4, and is for example integrally formed in one piece.Fitting thereto, on the inner circumference of valve body 50 alongitudinal groove 55 running in the axial direction of the valve bodyis formed which accommodates longitudinal rib 45 with a necessary degreeof movement play. Together, longitudinal rib 45 and longitudinal groove55 form a valve body guide that permits axial displacement of valve body51 on pipe socket 4, and at the same time form a lock against a rotationof valve body 51 in the circumferential direction relative to pipesocket 4 and relative to valve seat 50. In this way, during the time ofuse of filter 1, leaks of filter bypass valve 5 in its closed positionthat may occur due to a relative rotation of valve body. 51 and valveseat 50 are reliably prevented.

With regard to the further parts in FIG. 35 and their function,reference is made to the above description, in particular of FIGS. 8 and17.

FIG. 36 shows filter 1 of FIG. 35 in cross-section along the sectionalline H-H in FIG. 35. Radially outwardly, filter housing 2 with itscircumferential wall 20 is visible. Radially inward therefrom, in thebackground there is lower end plate 31 with a sealing ring bearer 34.The filter material body 30, in the form of the folded filter materialstrand, is situated on lower end plate 31. Here, annular valve body 51is situated radially inwardly from filter material body 30. Between theinner circumference of lower end plate 31 and the outer circumference ofvalve body 51, a small radially external part of valve seat 50,otherwise covered by valve body 51, can be seen.

Here again, the radially innermost part of filter 1 is formed by centralpipe socket 4 with perforations 42, of which two are visible here insection. On the outer circumference of pipe socket 4, on its sidepointing here to the right, longitudinal rib 45 protruding in the radialdirection and running in the axial direction of pipe socket 4 can beseen. Fitting longitudinal rib 45, on the inner circumference of annularvalve body 51 longitudinal groove 55 is formed, which accommodateslongitudinal rib 45. FIG. 36 illustrates that a rotation of valve body51 relative to central pipe socket 4 and relative to the valve seat 50attached non-rotatably on pipe socket 4 is not possible.

FIG. 37 shows the detail circled in FIG. 36 in an enlargedrepresentation. At left in FIG. 37, a part of central pipe socket 4 canbe seen with its longitudinal rib 45 situated on the outercircumference. Radially outwardly, i.e., here to the right, therefollows valve body 51 having longitudinal groove 55, which accommodateslongitudinal rib 45, in its inner circumference. In order not to hinderthe axial mobility of valve body 51 necessary for the valve function,longitudinal rib 45 and longitudinal groove 55 have adequate movementplay relative to one another.

Radially outwardly from valve body 51, a small part of lower end plate31 with filter material body 30 can also be seen.

FIG. 38 shows filter 1 in a further embodiment in longitudinal section,in a state in which it is installed on a coupling flange 60 of a device6. Filter 1 again has a cup-shaped filter housing 2 that is open at itsflange-side end face 21. Inside filter housing 2 there is situated acentral pipe socket 4 that is made up of a first flange-side pipe socketsegment 4.1 and a second pipe socket segment 4.2 that is remote from theflange and is tightly connected to end face 22 of filter housing 2remote from the flange, the two pipe socket segments 4.1 and 4.2 beingscrewed together.

On flange-side pipe socket segment 4.1, there are situated the parts offilter bypass valve 5, namely, at bottom, first valve seat 50, abovethis the axially displaceable valve body 51, and above this spring 52,which preloads the valve body 51 in the closing direction of filterbypass valve 5. On its end facing away from valve body 51, in theoperation-ready state shown in FIG. 38 spring 52 is supported andprestressed by spring support 53. Here as well, spring support 53 ispart of filter insert 3, more precisely of its central supportingelement 37.

On the upper end of flange-side pipe socket segment 4.1 there issituated a stop 43 on which the upper end of spring 52 abuts when filterhousing 2, and together with it filter insert 3, are separated from therest of filter 1. In this way, spring 52 and valve body 51 are securedagainst loss. At the upper side, stop 43 is realized with roof-shapedintroductory bevels 46 over which support arms 53′ are guided whenfilter 1 is assembled.

In addition to filter bypass valve 5, filter 1 according to FIG. 38 alsohas a return check valve 15 that covers inlet 11 and that preventsfilter 1 from running empty when there is a standstill of the liquidcircuit.

FIG. 39 shows filter 1 of FIG. 38 in a cross section along the sectionalline G-G in FIG. 38. Circumferential wall 20 of filter housing 2 runsradially externally. Radially inward therefrom, return check valve 15with spring tongue plate 18 is visible. Next, further radially inwardthere follows sealing ring 39′, then followed by valve seat 50. Stillfurther radially inward, flange-side pipe socket segment 4.1 issectioned, followed still further radially inwardly by threaded nipple63 of associated coupling flange 60. Outlet 12 of filter 1 is situatedin the center of FIG. 39.

FIG. 40 shows filter 1 of FIG. 38 in cross-section along the sectionalline H-H in FIG. 38. Here as well, radially externally firstcircumferential wall 20 of filter housing 2 is sectioned. Radiallyinward therefrom there is situated filter material body 30 of filterinsert 3 with central supporting element 37. At four points onsupporting element 37, uniformly spaced from one another in thecircumferential direction, spring supports 53 are integrally formed onsupporting element 37, and protrude radially inward. Radially inwardfrom supporting element 37 there then follow stop 43 and pipe socketsegments 4.1 and 4.2.

FIG. 41 shows filter housing 2 and filter insert 3 situated therein offilter 1 of FIG. 38 in longitudinal section, together forming theconstructive unit that is removed during maintenance of filter 1. Forthis purpose, by rotating filter housing 2 the flange-remote pipe socketsegment 4.2, with its lower outer threading 41″, is screwed out offlange-side pipe socket segment 4.1, filter insert 3 being carried alongdue to its frictional connection to filter housing 2. When filterhousing 2 has been completely unscrewed, filter insert 3 can be pulledout through the open underside of filter housing 2, and can be replacedby a fresh filter insert 3, including supporting element 37 with springsupport 53.

Seal 39 is here also part of filter insert 3, and is borne by a sealingring bearer 34 that is connected to lower flange-side end plate 31 offilter insert 3 via connecting webs 33, or is realized in one piecetherewith.

FIG. 42 shows filter housing 2 with filter insert 3 of FIG. 41, in anoblique view from below. Of filter insert 3, here its lower, flange-sideend plate 31, connecting webs 33, sealing ring bearer 34, and radiallyouter sealing ring 39 are visible. Radially inner sealing ring 39′ runsaround central perforation 31′ of end plate 31. Through perforation 31′,a part of inner supporting element 37 of filter insert 3 is visible.

FIG. 43 shows filter insert 3 of filter 1 of FIG. 38, in an oblique viewfrom below. The essential part of filter insert 3 is formed by itshollow cylindrical filter material body 30, covered at the underside byend plate 31 and at the upper side by end plate 32. From the radiallyexternal edge of lower end plate 31, a plurality (here five) ofconnecting webs 33, distributed uniformly around the circumference,extend downward in the axial direction, which bear sealing ring bearer34 on which outer sealing ring 39 is externally situated. Going aroundcentral perforation 31′ of lower end plate 31, radially inner seal 39′is again visible. Through perforation 31′, a small part of grid-shapedinner supporting element 37 is visible. Here, it is particularly clearthat the two sealing rings 39 and 39′ are parts of filter insert 3 thatare each replaced, without special measures, with filter insert 3 duringeach filter maintenance.

FIG. 44 shows filter insert 3 of FIG. 43 in an angled longitudinalsection. In the interior of filter material body 30, there is situatedsupporting element 37 with spring supports 53, distributed around theinner circumference of supporting element 37. On the lower side offilter insert 3, radially inner sealing ring 39′ runs around perforation31′ of lower end plate 31. Radially outer sealing ring 39 is situated onthe outer circumference of sealing ring bearer 34.

FIG. 45 shows filter insert 3 of FIG. 44 in cross-section according tothe sectional line F′-F′ in FIG. 44. Sealing ring 39 is radiallyoutwardly visible, borne by sealing ring bearer 34 running radiallyinward therefrom. Connecting webs 33 extend upward from sealing ringbearer 34. Further radially inward, second sealing ring 39′ issectioned.

FIG. 46 shows filter housing 2 of filter 1 of FIG. 38 in an oblique viewfrom below. In the interior of filter housing 2, flange-remote pipesocket segment 4.2 runs concentric to circumferential wall 20, with itsthreading 41″ for connection to second, flange-side pipe socket segment4.1, which remains on coupling flange 60 after a first assembly offilter 1 when filter housing 2 is unscrewed, as described above. In pipesocket segment 4.2, one of the perforations 42 provided therein isvisible, through which during operation of filter 1 filtered liquidmoves into the interior of central pipe socket 4.

FIG. 47 shows a coupling flange 60 of filter 1 having filter partsremaining thereon after removal of filter housing 2 and filter insert 3.The filter parts remaining on coupling flange 60 are flange-side pipesocket segment 4.1, with filter bypass valve 5 situated thereon, andreturn check valve 15 also situated thereon.

At the top in FIG. 47, stop 43, situated on the upper end of pipe socketsegment 4.1, is visible with top-side introductory bevels 46, and in theinterior of the upper end of pipe socket segment 4.1 its inner threading40″ is visible with which threading 41″ of flange-remote pipe socketsegment 4.2 (not present here) can be screwed together. Under stop 43,spring 52 of filter bypass valve 5 is visible, which preloads the valvebody 51 in the closing direction and presses it against valve seat 50.

Return check valve 15 includes a circular flexible valve membrane 15′and a spring tongue plate 18 situated above it, connected to the outercircumference of valve seat 50 via a plurality of locking connections 17distributed in the circumferential direction. Going around return checkvalve 15, coupling flange 60 of device 6 can be seen.

FIG. 48 shows the subject matter of FIG. 47 in longitudinal section;here it is particularly clear that flange-side pipe socket segment 4.1is screwed, with screw threading 40′ made on its outer region, i.e.,here its lower end region 40, onto a threaded nipple 63 situatedcentrally in coupling flange 60 and having a counter-threading 61′.Threaded nipple 63 is in turn permanently screwed to device 6 in thecenter of coupling flange 60 via a further screwed connection. The screwconnection of pipe socket segment 4.1 to threaded nipple 63 takes placeduring a first assembly of filter 1 and is secured against detachment byan anti-rotation lock 67 when filter housing 2 (not shown in FIG. 48) isunscrewed, together with flange-remote pipe socket segment 4.2, fromflange-side pipe socket segment 4.1.

On the outer circumference of flange-side pipe socket segment 4.1, theparts of filter bypass valve 5 are provided in the configurationdescribed above. At the top on pipe socket segment 4.1 there sits stop43 with top-side introductory bevels 46, which, during assembly offilter 1, guide spring support 53, or support arms 53′, situated infilter insert 3 into intermediate spaces 44 at the lower end of theintroductory bevels 46. In this way, only one filter insert 3 can beused having spring supports 53, or support arms 53′, in the number,shape, and distribution matching intermediate spaces 44.

Radially outward from valve seat 50, there is situated return checkvalve 15 which covers inlet 11, and which here has a separate membranebearer 15″.

FIG. 49 shows detail Y of FIG. 39 in an enlarged representation. At thefar left, a small part of threaded nipple 63 is visible, surroundedradially outwardly, i.e., to the right, by flange-side pipe socketsegment 4.1. Further outward, i.e., here to the right, follow valve seat50 and radially inner sealing ring 39′. At the right, i.e., radiallyoutward therefrom, a part of return check valve 15 with spring tongueplate 18 is still visible. The parts of return check valve 15 areconnected to valve seat 50 via locking connections 17; FIG. 49 shows oneof these locking connections 17. FIG. 49 further illustrates thatsealing ring 39′ is adapted in its course to the configuration andposition of locking connections 17, and here deviates radially outwardlyin each case. This curve of sealing ling 39′ adapted to the position oflocking connections 17 is also visible in FIGS. 42, 43, and 45.

FIG. 50 shows detail X of FIG. 40 in an enlarged representation, filtermaterial body 30 being visible here in the right part of FIG. 50, whichbody is supported radially inwardly, i.e., at left in the Figure, byinner supporting element 37. Made in one piece with supporting element37, here one of the spring supports 53 is visible, which engages in oneof the intermediate spaces 44 in stop 43. Radially inward from stop 43,i.e., to the left thereof in this Figure, small parts of pipe socketsegments 4.1 and 4.2 can be seen.

FIG. 51 shows a constructive unit including filter bypass valve 5 andreturn check valve 15 as parts of filter 1 of FIG. 38, in an obliqueview from below. At the upper end of flange-side pipe socket segment4.1, stop 43 is visible with introductory bevels 46 and intermediatespaces 44 between them. Under these is situated spring 52 of filterbypass valve 5, which preloads valve body 51 thereof in the closingdirection against valve seat 50.

In the lower part of FIG. 51, return check valve 15 is visible; here theview from below is directed to membrane bearer 15″ having perforationsfor inflowing liquid to be filtered. At the upper side, flexible valvemembrane 15′ is situated on membrane bearer 15″. Underneath membranebearer 15″, anti-rotation lock 67 is visible.

FIG. 52 shows the constructive unit of FIG. 51 together with couplingflange 60 and filter housing 2 having a filter insert 3, in an explodedview from below. At top in FIG. 52, filter housing 2 is visible, withfilter insert 3 situated therein. In the center part of the Figure, theconstructive unit of pipe socket segment 4.1 with filter bypass valve 5and return check valve 15 is visible. At the bottom in FIG. 52, couplingflange 60 of device 6 is visible, having threaded nipple 63 situated inits center having counter-threading 61′ for the threading (not visiblehere) provided in the lower end region of pipe socket segment 4.1.

FIG. 53 shows detail Z of FIG. 48 in an enlarged representation, inorder to illustrate the embodiment of return check valve 15 used here.At bottom in FIG. 53, a part of coupling flange 60 of device 6 isvisible, having unfiltered liquid duct 62 that leads to inlet 11 offilter 1. Here, inlet 11 is fashioned in the form of a plurality ofperforations, distributed in the circumferential direction, in membranebearer 15″. On the upper side of membrane bearer 15″ there is situatedflexible valve membrane 15′, loaded at the top by spring tongue plate 18which exerts a resetting force, acting in the closing direction, onvalve membrane 15′. The unit made up of membrane bearer 15″, valvemembrane 15′, and spring tongue plate 18 is connected to valve seat 50of filter bypass valve 5 by locking connections 17 mentioned above.

FIG. 54 shows detail W of FIG. 38 in an enlarged representation, herewith installed filter insert 3 and filter housing 2 put into place. Asthis Figure illustrates, in this assembled state radially inner sealingring 39′ presses valve membrane 15′ and the associated spring tongueplate 18 against membrane bearer 15″, and in this way provides a secureholding together and liquid-tight termination in this region. Outwardly,filter housing 2 is sealed in liquid-tight fashion by radially externalsealing ring 39, which is situated between filter housing 2 and couplingflange 60.

FIG. 55 shows filter insert 3 of filter 1 in a modified embodiment for afilter 1 without return check valve 15, in an oblique view from below.Differing from filter insert 3 for the previously described filter 1having return check valve 15, in filter insert 3 according to FIG. 55radially inner sealing ring 39′ is made circular, because here it doesnot require the particular shaping in order to take into account theposition of locking connections 17. In its remaining parts, filterinsert 3 according to FIG. 55 corresponds to the previously explainedexemplary embodiment.

FIG. 56 shows filter insert 3 of FIG. 55 in longitudinal section; hereas well the continuous circular curve of radially inner sealing ring 39′is visible. With regard to the further elements of filter insert 3according to FIG. 56, reference is made to the preceding description.

FIG. 57 shows filter 1 in a further embodiment in longitudinal section;for this embodiment, differing from the example according to FIG. 38, itis characteristic that no return check valve 15 is present. Inlet 11,which conducts liquid to be filtered from unfiltered liquid duct 62 tounfiltered side 13 of filter 1, is here always open. In other respects,filter 1 corresponds to the exemplary embodiment described on the basisof FIG. 38. Filter 1 according to FIG. 57 is suitable in particular forapplications in which it is not disturbing if the liquid flows out offilter 1 when there is a standstill of the liquid circuit.

FIG. 58 shows a constructive unit having filter bypass valve 5 as partof filter 1 of FIG. 57. Here, filter bypass valve 5 is again borne byflange-side pipe socket segment 4.1, on whose outer circumference thereare situated, going from bottom to top, valve seat 50, valve body 51,spring 52, and stop 43 having introductory bevels 46, and intermediatespaces 44 situated between them. Screw threading 40′ is attachedinwardly in the lower end region of pipe socket segment 4.1. In thelower part of FIG. 58, anti-rotation lock 67 is visible. Due to theabsence of the return check valve, in FIG. 58, compared to FIG. 51, nomembrane bearer having the other parts of the return check valve ispresent.

FIG. 59 shows the constructive unit of FIG. 58 in a state assembled tocoupling flange 60, in an oblique view from above. The state visiblehere results when filter housing 2 is removed, together with filterinsert 3, from coupling flange 60 for filter maintenance. When filterhousing 2 is unscrewed, the two pipe socket segments 4.1 and 4.2 areseparated from one another, because, due to anti-rotation lock 67,flange-side pipe socket segment 4.1 is secured against unscrewing fromcoupling flange 60. Running around anti-rotation lock 67 is annularunfiltered liquid duct 62, which leads to inlet 11 of filter 1. Atbottom left in FIG. 59, filtered liquid duct 61 is visible, throughwhich the filtered liquid is led off during operation of filter 1. Inthe example according to FIG. 59, coupling flange 60 is fashioned on abase 6′ that can be connected, via lines that lead further, to the restof device 6 having the liquid circuit with filter 1.

FIG. 60 shows filter housing 2 with filter insert 3 of filter 1 situatedtherein, of FIG. 57, in an oblique view from below. Radially inward fromdownward-pointing open end face 21 of circumferential wall 20 of filterhousing 2, there runs sealing ring 39, borne by sealing ring bearer 34.Sealing ring bearer 34 is connected to lower end plate 31 of filterinsert 3 by connecting webs 33. Circular inner sealing ring 39′ runsaround central perforation 31′ in lower end plate 31. Throughperforation 31′, a part of inner supporting element 37, with a shortsegment of one of the spring support 53, is visible. Filter materialbody 30 is situated radially outward from supporting element 37.

FIG. 61 shows filter housing 2 with filter insert 3 of FIG. 60, inlongitudinal section. Pipe socket segment 4.2 remote from the flange isplaced in sealing fashion into upper end face 22; here both filterhousing 2 and also pipe socket segment 4.2 are parts made of metal suchas steel plate. For mutual fixing and sealing, usefully filter housing 2and pipe socket segment 4.2 are welded to one another in the region inwhich they abut one another. At the lower end region of pipe socketsegment 4.2, threading 41″ is visible, used for screw connection toflange-side pipe socket segment 4.1.

At the height of lower end plate 31 of filter insert 3, circumferentialwall 20 has an inner diameter step 24 on which lower end plate 31 abutswith its upper side, whereby filter insert 3 is given a defined positionrelative to filter housing 2 in the axial direction. Moreover, filterinsert 3 is centered in the radial direction relative to filter housing2 by connecting webs present on lower end plate 31 on the one hand andby seal 36 on the inner circumference of upper end plate 32 on the otherhand. Radially outwardly situated sealing ring 39 is supported on anaxially downward-oriented circumferential surface of circumferentialwall 20. Radial inner sealing ring 39′ runs around central perforation31′ in lower end plate 31.

In the interior of filter material body 30, grid-type supporting element37 is situated, with which, here, spring supports 53 are realized in onepiece as radially inward-protuding ribs. Due to the angled course of thesection, here only one of the spring supports 53 is visible in the lefthalf of FIG. 61. Here, supporting element 37 is connected both to lowerend plate 31 and to upper end plate 32, for example by gluing orwelding.

FIG. 62 shows the constructive unit of FIG. 58, together with a couplingflange 60 and a filter housing 2 with filter insert 3 situated therein,in an exploded view. Filter insert 3 is pushed into filter housing 2from the open flange-side end face 21 of filter housing 2, and is heldin filter housing 2 by mutual friction or by a locking connection. Theconstructive unit visible below it includes the parts explained above onthe basis of FIG. 58, in particular filter bypass valve 5. At bottom inFIG. 62, coupling flange 60 is visible, here as part of a base 6′ thatis part of a device 6 that has a liquid circuit having liquid to befiltered. Threaded nipple 63 with its threading 61′ protrudes centrallyfrom coupling flange 60.

FIG. 63 shows the subject matter of FIG. 59 in longitudinal section. Incoupling flange 60, threaded nipple 63 is permanently and non-detachablyscrewed together with a lower threaded segment. Flange-side pipe socketsegment 4.1 is screwed to upper threading segment 61′ by means of itslower threading 40′, and is secured against detachment by anti-rotationlock 67. The parts of filter bypass valve 5, as explained above, aresituated on pipe socket segment 4.1. Because in the state shown in FIG.63, in which filter housing 2 and filter insert 3 are removed, springsupports 53 do not act on spring 52, here the spring is now expanded toits maximum length and abuts stop 43 with its upper end. In this way,loss of spring 52 and of valve body 5.1 is prevented.

FIG. 64 shows filter 1 in a further embodiment, in longitudinal section.This filter 1 is again a screw-on filter that is screwed onto a couplingflange 60 of a device 6 having a liquid circuit. Here, coupling flange60 again has a central threaded nipple 63 having a threading 61′ thatprotrudes from the plane of coupling flange 60. In addition to itsfilter housing 2 and filter insert 3, filter 1 has a base plate 16 thathas, radially inwardly, an inner threading 16′, and has radiallyoutwardly an outer threading 16″, and that has, in its region betweenthe two named threadings 16′, 16″, a plurality of perforationsdistributed in the circumferential direction as inlet 11 for liquid tobe filtered. Base plate 16 is screwed to threaded nipple 63 by threading16′. Filter housing 2 is screwed to outer threading 16″, which has forthis purpose screw threading 26 on the inside of the lower end region ofits circumferential wall 20.

In addition, a valve holder 58 is attached on threaded nipple 63 overbase plate 16, on or in which holder the parts of filter bypass valve 5are situated. Here, valve holder 58 is realized in two parts, having alower holder part 58.1 and an upper holder part 58.2 fixedly connectedtherewith. Here, valve seat 50 is fashioned in a base of lower holderpart 58.1. Valve body 51 is realized as a flat circular plate, and, inits closing position shown in FIG. 64, lies in sealing fashion on valveseat 50. By means of a helical pressure spring 52 situated in the valveholder 58, valve body 51 is preloaded with a force acting in the closingdirection. Here as well, spring 52 is again prestressed by a filterinsert 3, in that a spring support 53, realized in one piece withcentral supporting element 37 in filter material body 30, presses fromabove on spring 52 with an annular support collar that is orientedradially inward and then axially downward. Here, supporting element 37is connected only to lower end plate 31. The upper end of supportingelement 37 is situated at a distance from the underside of upper endplate 32.

Here, filter insert 3 has a lower end plate 31 that has on its undersidea circumferential seal 35 with which lower end plate 31 is placed insealing fashion onto the outer circumference of valve holder 58. Fromthe radially outer edge of lower end plate 31, connecting webs 33 againextend downward in the axial direction, which webs bear acircumferential sealing ring bearer 34 on whose outer circumferencethere is situated a radially external sealing ring 39 that seals filterhousing 2 against coupling flange 60. At the upper side, filter insert 3has a closed end plate 32.

FIG. 65 shows filter 1 in a further embodiment, in longitudinal section.In many parts, filter 1 corresponds to the example according to FIG. 64.Differing here is that filter bypass valve 5, in the example accordingto FIG. 65, has a covering body 59 assigned to it that ensures thatduring a filter maintenance with removal of filter housing 2 and offilter insert 3, filtered liquid outlet 12 is closed in order to preventdirt particles from moving from filter insert 3 or from filter housing 2into outlet 12 and from there into filtered liquid duct 61 of device 6.For this purpose, covering body 59 is situated on the upper side ofspring 52, and is preloaded by spring 52 with a force oriented upward,i.e., oriented away from valve body 51. In the assembled state of filter1 shown in FIG. 65, support arms 53′ of spring support 53 press, throughintroduction openings 53″ provided in the upper side of valve holder 58,onto the upper side of covering body 59, which in turn presses with itslower side on the upper end of spring 52, thus prestressing spring 52.

When filter housing 2 is removed from coupling flange 60 together withfilter insert 3, base plate 16 and a valve holder 58 with filter bypassvalve 5 remain on coupling flange 60. Here, support arms 53′ are removedupwardly from covering body 59, causing the covering body, under theaction of the force of spring 52, to come to lie against the undersideof the upper end wall of valve holder 58, with passages 58″ providedthere for filtered liquid. In this way, passages 58″ are closed, and nodirt particles can move into filtered liquid outlet 12.

So that support arms 53′ of spring supports 53 situated on supportingelement 37 can exert the required force on covering body 59, and, viathis, on spring 52 of filter bypass valve 5, here supporting element 37is supported with its upper end face, remote from the flange, on theinside of the upper end plate 32, remote from the flange, of filterinsert 3. Filter insert 3 is in turn supported on the inside of filterhousing 2 with its upper end plate 32 remote from the flange.

In addition, in this filter 1 supporting element 37 is situated in theinterior of filter material body 30 so as to be capable of rotationrelative to the rest of filter insert 3. For this purpose, supportingelement 37 lies with its upper end against the underside of upper endplate 32 of filter insert 3, but is not connected to this end plate 32.Supporting element 37 here does not have immediate contact withflange-side lower end plate 31 of filter insert 3. This capacity forrotation of supporting element 37 is required here because supportingarms 53′ of spring support 53 prevent supporting element 37 fromrotating as soon as supporting arms 53′ have entered into the associatedintroduction openings 53″ of valve holder 58, because valve holder 58 isseated in rotationally fixed fashion on threaded nipple 63. However, forthe further screwing of filter housing 2 onto base plate 16, filterhousing 2 must be further rotated together with filter insert 3 situatedtherein, which is enabled by the configuration of supporting element 37in filter insert 3 so as to be capable of rotation relative to the restof filter insert 3.

FIG. 66 shows filter 1 in a further embodiment, in longitudinal section.Filter 1 according to FIG. 66 corresponds in most of its parts to theexample according to FIG. 64. Different here is that in the exampleaccording to FIG. 66 a return check valve 15 is allocated to inlet 11.Return check valve 15 lies on the upper side of base plate 16 in theform of a flexible valve membrane 15′, and in this way covers theopenings in base plate 16 forming inlet 11. Return check valve 15 isautomatically opened by liquid to be filtered coming from unfilteredliquid duct 62. When there is a standstill of the liquid circuit, returncheck valve 15 ensures that filter 1 does not run empty.

FIG. 67 shows filter 1 in a further embodiment, in a first, angledlongitudinal section along the sectional line A-A in FIG. 68; herefilter 1 is shown in a state assembled to a coupling flange 60 of device6 such as an internal combustion engine. A threaded nipple 63 having anouter threading 61′ situated above the flange plane is part of couplingflange 60, threaded nipple 63 here being realized as a double nipple andbeing permanently screwed into device 6 with a lower outer threading.

Via an inner threading 16′, the base plate 16 of filter 1 is screwedtogether with upper outer threading 61′ of threaded nipple 63, thisscrew connection taking place during a first assembly of filter 1 oncoupling flange 60. A later detachment of this screw connection isprevented by an anti-rotation lock 67.

In addition, filter 1 has a filter housing 2, which here has the shapeof a downwardly open cup. In the lower edge part of its circumferentialwall 20, housing 2 has an inner threading 26, which here stands inscrewed engagement with outer threading 16″ of base plate 16. Both baseplate 16 and housing 2 are here parts made of plastic. The plastic partsare usefully manufactured as injection-molded parts, permittingmanufacture with a specific shape without subsequent cutting processing.Alternatively, base plate 16 and housing 2 can be parts made of metal,in particular pressure die-cast parts made of light metal such asaluminum.

In the interior of housing 2 there is situated a filter insert 3 that ismade up of a hollow cylindrical filter material body 30 having two endplates 31 and 32 enclosing it at its ends. In filter material body 30,there is situated a grid-type supporting element 37 that supports thisbody during operation. Via a central opening in lower end plate 32,filter insert 3 is placed into filter 1 with a sealing by a sealingcollar.

From the radially outer edge of lower end plate 32, distributed aroundits circumference, a plurality of connecting webs 33 extends downward inthe axial direction. Due to the angled course of the sectional plane ofFIG. 67, here only one of connecting webs 33 is visible in the left halfof FIG. 67.

At their lower ends, connecting webs 33 go into a circumferentialsealing ring bearer 34 having a cylindrical outer surface, on which acircumferential seal 39 is situated in the form of an elastic sealingring that is approximately square in its cross-section in the unloadedstate.

Filter insert 4 is set in a defined desired position relative to filterhousing 2 via its connecting webs 33.

In its radially lower outer edge region, base plate 2 extends radiallyoutward with an outer edge projection, under sealing ring bearer 34.

In the lower edge part of filter housing 2, there is fashioned a supportsurface that points downward in the axial direction, on which seal 39abuts with its upper side. When filter 1 is in place on coupling flange60, as shown in FIG. 67, seal 39 is pressed in the axial direction farenough that it expands radially outward and inward, and seals bothaxially and radially.

A plurality of openings, distributed in the circumferential direction ofbase plate 16, run through the radially outer part of base plate 16between its inner threading 16′ and its outer threading 16″, as inlet 11for liquid to be filtered. At the upper side, inlet 11 is covered by areturn check valve 15. Outlet 12 for filtered liquid runs centrallythrough base plate 16 and through threaded nipple 63.

In the center on the upper side of base plate 16, there is situated afilter bypass valve 5 that extends into supporting element 37. A valveholder 58 that forms a part of filter bypass valve 5 and whose basicshape is hollow-cylindrical, is fixedly connected, e.g.,friction-welded, at its lower end to base plate 16. Valve holder 58 ishere made up of two parts, namely a first, lower holder part 58.1, whichis fixedly connected to base plate 16, and a second, upper holder part58.2, connected to first holder part 58.1, here by a locking connection.Here, holder parts 58.1 and 58.2 are made of plastic.

In valve holder 58, at the bottom a valve seat 50 is fashioned thatworks together with a valve body 51 guided above it in axially movablefashion in valve holder 58. Above valve body 51, there is situated invalve holder 58 a spring 52 that exerts a force acting on valve body 51in its closing direction when filter insert 3 is placed into filter 1.

Above spring 52, here there is further situated in the valve holder 58an axially movable covering body 59 on whose underside the upper end ofspring 52 abuts and on whose upper side, as long as filter insert 3 isin place in the filter, spring support 53 abuts with its support arms53′, which hold covering body 59 in a position at a distance from theunderside of the upper end of the valve holder. In this position,covering body 59 releases a liquid passage 58″ in an upper end wall ofthe valve holder 58 for filtered liquid in the direction toward outlet12. In the depicted example, liquid passage 58″ is formed by a pluralityof smaller openings distributed in the circumferential direction, whichtogether provide the required flow cross-section.

When filter insert 3 is removed from filter 1, spring 52 pressescovering body 59 against the end wall of valve holder 58 and againstliquid passage 58″ situated there, and closes this passage. Thisprevents dirt particles from being able to fall into filtered liquidoutlet 12 during a filter maintenance.

Moreover, covering body 59 ensures an advantageous distribution of theforces acting between valve spring 52 and spring support 53.

Covering body 59 can also be omitted if, for the provided use of filter1, the protective function against dirt falling in and the function ofdistribution of forces can be done without.

Finally, at the upper end region of valve holder 58 another radiallyinward-pointing stop 58′ is integrally formed, which ensures alimitation of the movement upward, i.e., away from valve seat 50, ofcovering body 59 and of the upper end of spring 52.

Supporting element 37 again has spring support 53, here in the form of aplurality of supporting arms 53′ pointing downward in the axialdirection and distributed around the inner circumference of supportingelement 37. Due to the angled course of the sectional plane, in FIG. 67only one of supporting arms 53′ is visible in the left half of FIG. 67.Guided by positioning means described below, when filter 1 is assembledeach support arm 53′ extends from above through a fittingly positionedand dimensioned introduction opening 53″ in the upper side of valveholder 58, into the valve holder, thus coming to abut covering body 59,or, if this covering body is not present, immediately on the upper endof spring 52. In this way, support arms 53′ and introduction openings53″ form a key-lock coding that permits only the installation of afitting filter insert 3 in filter 1.

When filter housing 2, in which filter insert 3 has previously beenplaced, is screwed onto base plate 16, filter insert 3 moves, togetherwith housing 2, in the direction toward base plate 16, causing supportarms 53′ of spring support 53 to gradually prestress spring 52 more andmore strongly, until housing 2 has reached its end position, and spring52 has thereby reached its final prestressing. Spring 52 now pressesvalve body 51 in the closing direction against valve seat 50 with aspecifiable force. All parts of filter bypass valve 5 are configured soas to be fixed to the filter, i.e., are not parts of exchangeable filterinsert 3. Only spring support 53 is part of exchangeable filter insert3.

The valve membrane of return check valve 15 is clamped at its radiallyinner edge region between base plate 16 and lower holder part 58.1 ofvalve holder 58, which makes separate holding means for return checkvalve 15 dispensable.

During operation of filter 1, liquid to be filtered flows through anunfiltered liquid duct 62 in the radially outer part of the couplingflange 60, and through inlet 11, as well as through return check valve15, to an unfiltered side 13, external to filter insert 3, of filter 1.From there, the liquid flows, while depositing solid particles, throughfilter material body 30 of filter insert 3, in the radial directioninward to filtered side 14 of filter 1. From there, the filtered liquidflows through the interior of supporting element 37, through liquidpassage 58″ in valve holder 58, and then through central outlet 12 andthrough the interior of threaded nipple 63, into a filtered liquid duct61 in coupling flange 60.

If the pressure difference between unfiltered side 13 and filtered side14 of filter 1 exceeds a specifiable boundary value, valve body 51 islifted off from its valve seat 50, against the force of valve spring 52,and an immediate flow path is released for the liquid from unfilteredside 13 to filtered side 14, bypassing filter material body 30 of filterinsert 3.

When there is a standstill of the liquid circuit, return check valve 15ensures that no liquid flows out from the interior of filter 1, so that,when there is a restart of the liquid circuit, an immediate supply offiltered liquid to downstream consumers is ensured.

FIG. 68 shows filter 1 of FIG. 67 in cross-section along sectional lineB-B in FIG. 67. Externally, in FIG. 68 filter housing 2 is visible,whose circumferential wall 20 is here sectioned. Radially inwardtherefrom is situated filter insert 3, through whose filter materialbody 30 the section runs. Distributed around the circumference of filterinsert 3, the four connecting webs 33 are visible from above, extendingfurther downward in the axial direction. In the interior of filtermaterial body 30, there is situated grid-type supporting element 37,which supports the filter material body during operation. Furtherradially inward therefrom is situated valve holder 58, in which theparts of filter bypass valve 5 are situated, of which here only a partof valve spring 52 and, in the center, a part of valve body 51 arevisible. In FIG. 68, sectional line A-A illustrates how the longitudinalsection shown in FIG. 67 runs through filter 1.

FIG. 69 shows detail V of filter 1 of FIG. 68 in an enlargedrepresentation. At the upper right in FIG. 69, a part of filter materialbody 30 of filter insert 3 can be seen. Under it, a segment ofsupporting element 37 is visible. Further downward, a segment of valveholder 58 is then visible; here it can be seen that the valve holder 58is made up of a first holder part 58.1 and a second holder part 58.2which are plugged into one another over a part of their height. The twoholder parts 58.1 and 58.2 are connected to one another by lockingconnections 58.3, of which one is visible in section in FIG. 69. Furtherdownward, finally, a part of valve body 51 is visible.

FIG. 70 shows filter 1 of FIG. 67 in cross-section according tosectional line D-D in FIG. 67. Here as well, radially outwardly filterhousing 2 is again visible, whose circumferential wall 20 is sectioned.Radially inwardly therefrom there is again situated filter insert 3 withfilter material body 30, and connecting webs 33 extending axiallydownward. Radially inward from filter material body 30 there is situatedthe associated supporting element 37. Radially inwardly therefrom inturn there is situated valve holder 58. As FIG. 7 illustrates, valveholder 58 has, on its upper side visible here, a number of introductionopenings 53″ through which support arms 53′ of spring support 53 offilter insert 3 extend into the interior of valve holder 58. Moreover,in addition to introduction openings 53″ in the upper side of valveholder 58 there is present a liquid passage 58″ in the form of aplurality of openings distributed in the circumferential direction,through which filtered liquid flows during operation of filter 1.

FIG. 71 shows detail U of filter 1 of FIG. 70, in an enlargedrepresentation. At bottom right, a part of filter material body 30 canbe seen. Radially inwardly, i.e., in FIG. 71 above this at the left, apart of supporting element 37 is visible. Radially inwardly therefrom,upper part 58.2 of the valve holder 58 is visible, in whose upper sideintroduction openings 53″ for support arms 53′ and the openings formingliquid passage 58″ can be seen. Here, introduction openings 53″ andsupport arms 53′ form a key-lock coding that permits only theinstallation of a particular filter insert 3, having support arms 53′ ina fitting configuration, number, and shape, into filter 1.

FIG. 72 shows filter 1 of FIG. 67 in a second longitudinal section,rotated relative to FIG. 67, along sectional line C-C in FIG. 68. In theinterior of the valve holder 58, here valve body 51, valve spring 52,and covering body 59 can be seen. Support arms 53′ of spring support 53of filter insert 3 abut the upper side of covering body 59, and via thisupper side compress spring 52. As a result, spring 52 exerts aspecifiable force acting in the closing direction on valve body 51 offilter bypass valve 5. At the upper right on valve holder 58, an openingof liquid passage 58″ is visible through which filtered liquid flowsduring operation of filter 1.

With regard to the further individual parts and reference charactersappearing in FIG. 72, reference is made to the preceding description.

FIG. 73 shows detail X of filter 1 of FIG. 72 in an enlargedrepresentation. At the bottom, a small part of base plate 16 can beseen, to whose upper side first holder part 58.1 of valve holder 58 isfixedly connected, e.g., welded. At lower left in FIG. 73, valve seat 50is visible, fashioned as part of first holder part 58.1. Valve body 51,in its closed position, here abuts valve seat 50, valve body 51 havingon its surface facing the valve seat 50 an elastomeric coating 57 inorder to improve the sealing effect in the closed position. Spring 52,in the form of a helical pressure spring, runs around an upper part ofvalve body 51. Radially externally, i.e., here to the right of firstholder part 58.1, a part of second holder part 58.2 can be seen, holderparts 58.1 and 58.2 being connected to one another by lockingconnections 58.3, of which one is visible in FIG. 73.

Radially outwardly from valve body 53, i.e., to the right thereof inFIG. 73, a small part of filter insert 3 is visible with filter materialbody, lower end plate 31, sealing collar 35, and grid-type supportingelement 37. Opening 31′, by which filter insert 3 is placed in sealingfashion onto second holder part 58.2 of valve holder 58, is situatedcentrally in lower end plate 31.

At lower right in FIG. 73, finally, a part of return check valve 15 isvisible, whose valve membrane 15′ is clamped, at its radially inner edgeregion, in sealing fashion between base plate 16 and holder part 58.1 ofvalve holder 58.

FIG. 74 shows filter 1 of FIG. 72 in cross-section along sectional lineI-I in FIG. 72. Radially outwardly, filter housing 2 of filter 1 issituated, circumferential wall 20 of housing 3 here again beingsectioned. Further radially inward, filter insert 3 is visible withfilter material body 30, here sectioned, supported radially inwardly bysupporting element 37. Radially inward from supporting element 37, valveholder 58 is visible, in which covering body 59 is situated. In theexact center of FIG. 74, finally, valve body 51 is partially visiblefrom above.

FIG. 75 shows detail W of filter 1 of FIG. 74 in an enlargedrepresentation. At left, a part of filter material body 30 of filterinsert 3 is visible. To the right thereof runs supporting element 37.Further to the right, there then follow segments of valve holder 58 andof covering body 59, which is displaceably guided in the valve holder 58axially, i.e., perpendicular to the plane of the drawing of FIG. 75, butis secured against rotation in the circumferential direction byinterlocking contours.

FIG. 76 shows filter 1 in the same representation as in FIG. 67, buthere with filter bypass valve 5 in the open position. The state offilter bypass valve 5 shown in FIG. 76 results when in filter 1 apressure difference prevails between the unfiltered side 13 and filteredside 14 that exceeds a specifiable boundary value, for example whenfilter material body 30 of filter insert 3 is clogged with previouslyfiltered-out dirt particles. In this case, the liquid at the unfilteredside 13 of filter 1 exerts on valve body 51 of filter bypass valve 5 aforce acting in the opening direction that is greater than the forceexerted in the closing direction by valve spring 52. The force acting inthe opening direction displaces valve body 51 in the direction away fromits valve seat 50, thus releasing an immediate flow connection fromunfiltered side 13 to filtered side 14 of filter 1, through a valvethrough-opening 50′, bypassing filter material body 30. As soon as thepressure difference between unfiltered side 13 and filtered side 14falls below the specifiable threshold value, the force of valve spring52 again predominates, so that valve body 51 is then moved back into itsclosing position, in which it is seated in sealing fashion on valve seat50.

With regard to the further individual parts and reference characters inFIG. 76, reference is made to the preceding description.

FIG. 77 shows detail Y of filter 1 of FIG. 76 in an enlargedrepresentation. At the right in FIG. 77, valve body 51 with elastomericcoating 57 is partly visible, having a distance from its valve seat 50,so that valve through-opening 50′ of filter bypass valve 5 is released.Thus, here there is an immediate flow connection from unfiltered side 13to filtered side 14 of filter 1. At the top in FIG. 77, a part of valvespring 52 is visible, here compressed by the force produced by thepressure difference between unfiltered side 13 and filtered side 14. Tothe left of valve body 51 and spring 52, holder parts 58.1 and 58.2 ofvalve holder 58 are visible. Further to the left thereof, a small partof filter insert 3 is also visible. Finally, at bottom in FIG. 77 asmall part of base plate 16 is visible, bearing at its upper side valveholder 58 with filter bypass valve 5 and return check valve 15, herevisible only in small part.

FIGS. 78 through 81 show filter coupling flange 60 with base plate 16attached thereon together with valve holder 58, and having a filterinsert 3, shown only partially for reasons of clarity, in various phasesof the installation of filter insert 3. Here, of filter insert 3, onlyits lower end plate 31, with connecting webs 33, sealing bearer 34, andseal 39; are shown in a front view, as well as grid-type supportingelement 37 in longitudinal section.

FIG. 78 shows filter coupling flange 60 with base plate 16 of filter 1screwed thereon in a front view, and with filter insert 3 in a firstphase of the installation of filter insert 3 during a filtermaintenance. As described above, filter insert 3 has a spring support 53having a plurality of support arms 53′ that enter through introductionopenings 53″ in valve holder 58 into the interior thereof. So thatsupport arms 53′ reliably reach the fitting position for this purpose,seen in the circumferential direction, on filter insert 3 there areprovided, in addition to support arms 53′, first positioning elements37′ that work together with second positioning elements 37″ on valveholder 58. Here, first positioning elements 37′ are situated on theinner circumference of supporting element 37, between support arms 53′,and have the form of oblong ribs or webs running in the axial directionand protruding radially inward. Second positioning elements 37″ areformed by a respective declining bevel running in the circumferentialdirection of the valve holder 58 on the upper end of its outercircumference, going over into an axial groove on the outercircumference of valve holder 58. In FIG. 78, filter insert 3 is justbeing placed, by means of central opening 31′ of its lower end plate 31,into an arbitrary position, regarded in the circumferential direction,from above onto the valve holder 58; here support arms 53′ and firstpositioning elements 37′ have not yet come into contact with the valveholder 58.

FIG. 79 shows the subject matter of FIG. 78 in the same representation,here in a second phase of the installation of filter insert 3. Here,filter insert 3 is moved further downward relative to valve holder 58,causing first positioning elements 37′ to come into contact with secondpositioning elements 37″. Here, first positioning elements 37′ abut,with their downward-pointing end surface, seen in the circumferentialdirection, on some point of the bevels forming a part of secondpositioning elements 37″, at the top on valve holder 58.

FIG. 80 shows the subject matter of FIGS. 78 and 79 in the samerepresentation, here in a third phase of the installation of filterinsert 3. Here, as a result of a rotation in the circumferentialdirection usefully carried out together with the rotational movement ofthe filter housing 2 (not shown here) when it is screwed onto base plate16, filter insert 3 has now reached a position in which firstpositioning elements 37′ have arrived at the lower end of the bevels ofsecond positioning elements 37″, and now, seen in the axial direction,are positioned exactly over the vertical groove as second part of secondpositioning elements 37″. A further rotation of supporting element 37with first positioning elements 37′ relative to valve holder 58 is nowno longer possible. For this reason, supporting element 37 is heresituated so as to be capable of rotation in filter insert 3 relative tolower end plate 31 of filter insert 3.

FIG. 81 shows the subject matter of FIGS. 78 through 80 in the samerepresentation, here in a fourth phase of the installation of filterinsert 3. First positioning elements 37′ now enter into the axialgrooves, forming part of second positioning elements 37″, on the outercircumference of valve holder 58. At the same time, support arms 53′ ofspring support 53 enter, through introduction openings 53″ provided forthem, into the interior of valve holder 58, and move covering body 59situated there and explained above downward, thus prestressing valvespring 52 of filter bypass valve 5. The mutually fitting finding ofsupporting element 37 and valve holder 58 is thus brought aboutautomatically, without requiring particular attention on the part ofmaintenance personnel with regard to the mutual positioning of the namedparts.

Due to the fact that separate positioning elements 37′ are provided onfilter insert 3, support arms 53′ of spring support 53 are relieved ofall forces connected with the positioning, in particular forces actingin the circumferential direction.

FIG. 82 shows filter coupling flange 60 with base plate 16 of filter 1screwed thereon, and with valve holder 58, in a front view, withoutfilter insert 3 and without filter housing 2. At bottom in FIG. 82, apart of device 6 having filter 1 is shown with coupling flange 60, towhich base plate 16 of filter 1 is connected. Base plate 16 has on itsouter circumference outer threading 16′, used to screw on filter housing2 (not shown here). Return check valve 15 is situated radiallyexternally on the upper side of base plate 16. Valve holder 58, withfilter bypass valve 5 housed therein, is attached centrally on baseplate 16. Valve holder 58 is made up of the two holder parts 58.1 and58.2, connected to one another via locking connections 58.3. On theupper side of valve holder 58 there can be seen introduction openings53″ for support arms 53′ of spring support 53, as well as liquid passage58″ for filtered liquid. The above-described second positioning elements37″ are situated in the upper region of the outer circumference of valveholder 58.

In the example shown, four support arms 53′ and four first and secondpositioning elements 37′ and 37″ are provided; however, a smaller orlarger number is also possible.

FIG. 83 shows base plate 16 of filter 1 with valve holder 58 and valvebody 51 and having return check valve 15, but without valve spring 52and covering body 59, in a sectioned view. Base plate 16, visible atbottom in FIG. 83, has on its inner circumference inner threading 16′,which is used to screw base plate 16 onto coupling flange 60 (not shownhere).

On its outer circumference, base plate 16 has outer threading 16″, whichis used to screw on filter housing 2, also not shown here. Underneathouter threading 16″, there runs a radially outward-protruding outer edgeprojection of base plate 16.

Openings for the supply of liquid to be filtered run through the regionof base plate 16 situated between inner threading 16′ and outerthreading 16″. At the upper side, inlet 11 is covered by return checkvalve 15. Valve membrane 15′ of return check valve 15 is mounted at itsinner edge region on base plate 16, in that a lower edge region of thevalve holder 58 clamps the edge region from above. Outlet 12 runscentrally through base plate 16.

Valve holder 58 is fixedly connected to the upper side of base plate 16.Valve holder 58 is made up of the two holder parts 58.1 and 58.2, whichare connected to one another via locking connections 58.3. In theinterior of valve holder 58, valve body 51 of filter bypass valve 5 isguided movably in the axial direction. Valve body 51 works together withvalve seat 50 fashioned at the bottom on valve holder 58.

In the upper end face of valve holder 58, introduction openings 53″ forsupport arms 53′ and liquid passage 58″ for filtered liquid can be seen.On the axially upper end region of the outer circumference of valveholder 58, at right in FIG. 83 one of the two positioning elements 37″is visible.

FIG. 84 shows base plate 16 of filter 1 with the parts according to FIG.83, and in addition having valve spring 52 and covering body 59, inlongitudinal section. Here a state is shown that arises when filterinsert 3 is removed. In this state, valve spring 52 is not prestressedby spring support 53 with its support arms 53′, so that valve spring 52can extend to its maximum length provided by valve holder 58. This hasthe result that now covering body 59 has moved into an upward-displacedposition in which it abuts a stop 58′ at the upper end of valve holder58. In this position, covering body 59 closes all the openings formingliquid passage 58″ in the upper end face of the valve holder 58. In thisway, it is ensured that in this state a disturbing or damaging fallingin of dirt particles, through liquid passage 58″ into outlet 12 forfiltered liquid, during a filter maintenance is not possible.

Outlet 12, and inner threading 16′ situated therein, are again visiblein the center of base plate 16. In the lower region of outlet 12,elements of anti-rotation lock 67 are visible, which ensures that baseplate 16, after being screwed onto threaded nipple 63 of coupling flange60 during first assembly of filter 1, is fixed thereto and can no longerbe screwed off.

Return check valve 15 is again visible on the radially outer part of theupper side of base plate 16.

FIG. 85 shows filter housing 2 with filter insert 3 placed therein, in alongitudinal section. Radially outwardly, screw housing 2 of filter 1,with circumferential wall 20, can be seen. In the interior of filter 1,filter insert 3 is situated with its above-described individual parts.In the interior of filter material body 30 of filter insert 3, there issituated supporting element 37, having on its inner circumference springsupport 53 having support arms 53′ distributed in the circumferentialdirection and having first positioning elements 37′ integrally formedthereon in one piece. Here, supporting element 37 is introduced frombelow, through central opening 31′ in lower end plate 31, into theinterior of filter insert 3 and of filter material body 30, and, duringoperation of filter 1, supports filter material body 30 radiallyinwardly against collapse. Here, supporting element 37 terminates at adistance from upper end plate 32; alternatively, however, it could alsobe realized extending up to this end plate 32.

The four connecting webs 33, spaced uniformly from one another in thecircumferential direction, extend downward in the axial direction fromthe radially outer edge of lower end plate 31 of filter insert 3. Innerthreading 26 is provided on the inner circumference of circumferentialwall 20 of filter housing 2, close to its lower end face 21. On theradially outward-oriented surface of connecting webs 33, a respectivebulge or locking cam 33′ is integrally formed, somewhat abovecircumferential sealing bearer 34, which bulge or cam provides an easilydetachable locking of filter insert 3 in filter housing 2 in interactionwith a locking recess 28′ on the inner circumference of circumferentialwall 20. In this way, filter insert 3 is determined in a defined mannerin its position relative to screw housing 3, by means of its connectingwebs 33.

At their axially lower end, connecting webs 33 go over intocircumferential sealing bearer 34, here made in one piece with the webs,on which bearer sealing ring 39 is situated.

The unit shown in FIG. 85 of filter housing 2 and filter insert 3 isscrewed off from coupling flange 60, or from base plate 16 permanentlyattached thereon, when there is a filter maintenance. All parts offilter bypass valve 5, with the exception of spring support 53, remainon base plate 16, and are thus elements fixed to the filter.Subsequently, used filter insert 3 can be withdrawn from housing 2 andreplaced by a fresh filter insert 3. Because seal 39 is part of filterinsert 3, seal 39 is here automatically also replaced. After screwingthe unit made up of housing 2 and fresh filter insert 3 onto base plate16, filter 1 is again ready for operation.

With regard to the further individual parts and reference charactersshown in FIG. 85, reference is made to the preceding description.

FIG. 86 shows a filter bypass valve 5 of filter 1 in a modifiedembodiment, together with a coupling flange 60, in longitudinal section.This filter bypass valve 5 is provided for filter 1 having a centralpipe socket 4 made up of two pipe socket segments 4.1 and 4.2, asdescribed above. In FIG. 86, only flange-side pipe socket segment 4.1 isvisible, here provided in its lower end region 40 with an outer screwthreading 40′ with which pipe socket segment 4.1 is permanently screwedinto an inner threading 61′ centrally in coupling flange 60. A threadednipple, as provided in some exemplary embodiments described above, isthus not present here.

On a center region, seen in the longitudinal direction, of pipe socketsegment 4.1, annular valve seat 50 is seated so as to benon-displaceable in the axial direction, the valve seat havingthrough-openings 50′ that run parallel to the longitudinal direction ofpipe socket segment 4.1. On the upper side of valve seat 50 there issituated the also annular valve body 51, guided in displaceable fashionon pipe socket segment 4.1, in the axial direction thereof. On its sidefacing the valve seat 50, valve body 51 has an elastomeric coating 57for improving the sealing effect in the closed state of filter bypassvalve 5. Above valve body 51 is situated spring 52 surrounding pipesocket segment 4.1, which spring here abuts stop 43 with its upper end,in the absence of filter insert 3. At the upper side, stop 43 has aplurality of roof-shaped introductory bevels 46 situated in thecircumferential direction of pipe socket segment 4.1, between whichthere are respectively situated intermediate spaces 44 for guidingthrough support arms 53′ of spring support 53.

As FIG. 86 further illustrates, in its depicted closed position valvebody 51 covers perforations 42 made in pipe socket segment 4.1. Whenvalve body 51 is in its open position, i.e., is displaced upwardrelative to valve seat 50, perforations 42 are at least partly released,whereby a very short immediate flow path from inlet 11 to outlet 12 isreleased, bypassing filter insert 3.

FIG. 87 shows filter 1 in a further embodiment, in longitudinal section.In large part, filter 1 corresponds to the exemplary embodimentaccording to FIG. 66; in particular, filter housing 2 and filter insert3 are identical in the two examples. Different in these two exemplaryembodiments is that filter 1 according to FIG. 87 does not have a baseplate, and is designed for a coupling flange 60 not having a centralthreaded nipple. Instead of central threaded nipple, coupling flange 60in FIG. 87 has a collar having an outer threading 61′ onto which aninner threading 26 on filter housing 2 can be screwed. This screwconnection is sealed by sealing ring 39.

As do all other exemplary embodiments, filter 1 according to FIG. 87also has a filter bypass valve 5, here again situated in a valve holder58. Valve holder 58 is here again realized in two parts, having a first,lower holder part 58.1, and a second, upper holder part 58.2, which hereare for example sheet metal parts. Lower holder part 58.1 has adownward-protruding hollow cylindrical segment that forms outlet 12 andis pressed into a fittingly shaped and dimensioned opening in the centerof coupling flange 60. After first assembly, valve holder 58 is thusseated in a press-fit seating in coupling flange 60, from which it isthen no longer detached in normal operation of filter 1. In itsremaining parts and functions, filter bypass valve 5 in FIG. 87corresponds to filter bypass valve 5 as already described in FIG. 64.With regard to the other parts and reference characters in FIG. 87,reference is made to the preceding description.

A return check valve 15 is here attached immediately on coupling flange60, and is thus here not an integral component of filter 1.

FIG. 88 shows filter bypass valve 5 and return check valve 15 of FIG. 87in the state connected to coupling flange 60, in an oblique view fromabove; here filter housing 2 and filter insert 3 are unscrewed fromcoupling flange 60. On the upper side of coupling flange 60, the collarthereof, with an outer threading 61′, is radially outwardly visible.Radially inwardly therefrom, return check valve 15, here attachedimmediately on coupling flange 60, is visible. In the center of couplingflange 60, valve holder 58 is attached, with filter bypass valve 5situated therein, of which only spring 52 is immediately visible.

FIG. 89 shows filter 1 in a further embodiment in longitudinal section,this filter 1 corresponding in large part to the exemplary embodimentaccording to FIG. 87. Differing from the example according to FIG. 87,in the example according to FIG. 89 a covering body 59 is additionallysituated in valve holder 58. Covering body 59 is situated between theupper end of spring 52 of filter bypass valve 5 and the underside ofupper end face of the valve holder 58. In the assembled state ready foroperation of filter 1, as shown in FIG. 89, support arms 53′ of springsupport 53 of filter insert 3 engage from above through introductionopenings 53″ of valve holder 58 into this valve holder, and press ontospring 52 via covering body 59. In this way, spring 52 is prestressed,and exerts a specifiable preloading force on valve body 51 of filterbypass valve 5. At the same time, in this way covering body 59 is heldat an axial distance from passages 58″ in the upper side of valve holder58, making possible a flow of filtered liquid from the interior offilter insert 3 through outlet 12 to filtered liquid duct 61 in couplingflange 60 of device 6.

If, as shown in FIG. 90, filter housing 2 is screwed off from couplingflange 60 together with filter insert 3, then spring 52 presses coveringbody 59 upward against the underside of the upper end face of the valveholder 58, and then closes passages 58″ situated there. In this way,dirt particles are reliably prevented from falling into outlet 12 andinto filtered liquid duct 61.

With regard to the further individual parts and functions of filter 1according to FIGS. 89 and 90, reference is made to the precedingdescription, in particular of FIG. 87.

FIG. 91 shows filter 1 in a further embodiment, in a state assembled ona coupling flange 60, in longitudinal section. Filter 1 has a one-piececentral pipe socket 4 that is fixedly connected at its upper end region41 to flange-remote end face 22 of filter housing 2, for example bywelding. Characteristic for this exemplary embodiment is that centralpipe socket 4 has in its lower flange-side end region 40 an innerthreading 40′ by which filter housing 2 is screwed onto a fitting outerthreading 61′ on a threaded nipple 63 attached centrally in couplingflange 60.

Filter bypass valve 5 of filter 1 according to FIG. 91 is situated inthe upper region of central pipe socket 4, and corresponds to theembodiment as described above in FIGS. 1 and 4 through 6, to whichreference is made in this regard.

Finally, FIG. 92 of the drawing shows filter 1 of FIG. 91 in a stateremoved from coupling flange 60, in longitudinal section. Filter insert3 is seated with a frictional fit on central pipe socket 4 in theinterior of filter housing 2, so that when filter housing 2 is unscrewedfrom threaded nipple 63 filter insert 3 is carried along with it. In thestate shown in FIG. 92, filter insert 3 can be withdrawn downward fromfilter housing 2, and replaced by a new, fresh filter insert 3. Springsupport 53, which prestresses spring 52 of filter bypass valve 5, ishere as well provided on filter insert 3, specifically on its centralsupporting element 37. When filter insert 3 is withdrawn from filterhousing 2, spring 52 is relieved of tension until it abuts stop 43 withits lower end. Stop 43 is here realized in the form of a sheet metalsleeve that is attached in axially non-displaceable fashion on the outercircumference of pipe socket 4, and that is axially supported at itslower end in some of the perforations 42 made in pipe socket 4. Thus,spring 52 and valve body 51 of filter bypass valve 5 are here as wellsecured against loss.

Here as well, seal 39 is again part of filter insert 3, and is situatedon a circumferential sealing ring bearer 34, which is again connected tolower, flange-side end plate 31 of filter insert 3 via connecting webs33, or is realized in one piece therewith.

As is apparent from the foregoing specification, the invention issusceptible of being embodied with various alterations and modificationswhich may differ particularly from those that have been described in thepreceding specification and description. It should be understood that Iwish to embody within the scope of the patent warranted hereon all suchmodifications as reasonably and properly come within the scope of mycontribution to the art.

LIST OF REFERENCE CHARACTERS

-   1 filter-   10 connecting flange-   11 inlet-   12 outlet-   13 unfiltered side-   14 filtered side-   15 return check valve-   15′ valve membrane-   15″ membrane bearer-   16 base plate-   16′ screw threading internal on 16-   16″ screw threading external on 16-   17 locking connection between 15″ and 50-   18 spring tongue plate-   2 filter housing-   20 circumferential wall-   20′ screw cover-   21 flange-side end face-   22 flange-remote end face-   23 tool attachment projection-   24 inner diameter step-   25 threaded connector on 22-   25′ weld seam-   26 screw threading-   28 recesses in 25-   28′ locking recesses internal in 20-   3 filter insert-   30 filter material body-   31 lower, flange-side end plate-   31′ central perforation in 31-   32 upper, flange-remote end plate-   32′ central perforation in 32-   33 connecting webs-   33′ locking cams on 33-   34 sealing ring bearer-   35 seal/sealing lip on 31-   36 sealed/sealing lip on 32-   37 inner support body-   37′ first positioning means on 3-   37″ second positioning means on 58-   38 axial struts of 37-   39 first sealing ring (outer)-   39′ second sealing ring (inner)-   4 central pipe socket-   4.1 first, flange-side pipe socket segment-   4.2 second, flange-remote pipe socket segment-   40 outer end region-   40′ screw threading on 40-   40″ threading on 4.1 for 4.2-   41 inner end region-   41′ threading on 41-   41″ threading on 4.2 for 4.1-   42 perforations-   43 stop-   43.1 stop collar-   43.2 stop tongues-   43.3 stop tab-   44 intermediate spaces-   45 longitudinal rib on 4-   46 introductory bevels-   47 anti-rotation lock-   47′ anti-rotation lock ring-   48 cam on 47′-   49 longitudinal guide for 37-   5 filter bypass valve-   50 valve seat-   50′ through-opening(s)-   51 valve body-   52 spring-   53 spring support-   53′ support arms-   53″ introduction opening(s) for 53′ in 58-   54 intermediate ring-   55 longitudinal groove in 51-   56 inner threading in 50-   57 elastomeric coating on 50, 51-   58 valve holder-   58.1 first, lower holder part-   58.2 second, upper holder part-   58.3 locking connection between 58.1 and 58.2-   58′ stop for 52 in 58-   58″ passage-   59 covering body-   6 device having liquid circuit-   6′ base-   60 coupling flange-   61 filtered liquid duct-   61′ counter-threading in/on 61-   62 unfiltered liquid duct-   63 threaded nipple-   65 stop for 50-   67 anti-rotation lock

1. Exchangeable filter insert for a filter, the filter having a filterhousing comprising an inlet for liquid to be filtered, an outlet forfiltered liquid, a filter bypass valve having a valve seat and a valvebody guided so as to be movable in relation to the valve seat andpreloaded in a closing direction, the valve seat being situated in thefilter so as to be fixed to the filter, the valve body being guided inthe filter so as to be fixed to the filter, a spring configured andarranged to preload the valve body in the closing direction and beingguided in the filter so as to be fixed to the filter, the exchangeablefilter insert comprising: a configuration enabling the filter insert tobe positioned to separate an unfiltered side and a filtered side of thefilter from one another; and a spring prestresser support configured, inthe state in which the filter insert is positioned in the filterhousing, to support and prestress the spring of the filter bypass valveat its end oriented away from the valve body.
 2. Exchangeable filterinsert as recited in claim 1, wherein: the spring prestresser support isfashioned by a or on a supporting element that forms a part of thefilter insert.
 3. Exchangeable filter insert as recited in claim 1,further comprising: a hollow cylindrical filter material body and twoend plates oppositely disposed in relation to the hollow cylindricalfilter body; and the spring prestresser support having a support surfacepositioned within the exchangeable filter insert and spaced from each ofthe two end plates.
 4. Exchangeable filter insert as recited in claim 1,wherein: the filter insert is configured to be manufactured with adifferent axial length or position of the spring prestresser support;and in this way a prestressing of the spring, and thus an openingpressure of the filter bypass valve, is configured to be modified. 5.Exchangeable filter insert as recited in claim 1, wherein the filterhousing of the filter to be used with the exchangeable filter insertincludes a central pipe socket, wherein the valve seat is fashioned onor attached to the pipe socket, wherein the valve body and the springare guided on the pipe socket, wherein a stop is situated on a side ofthe spring facing away from the valve body having one or more openintermediate spaces distributed around a circumference of the stop, andwherein: the spring prestresser support of the exchangeable filterinsert has a plurality of support arms shaped and configuredcorresponding to a shape and configuration of open intermediate spacesin the stop or of introduction openings in a valve holder of the filter,such that during positioning of the filter insert into the filterhousing the support arms can be guided through the one or more openintermediate spaces or the introduction openings, and such that thesupport arms form with the one or more open intermediate spaces or withthe introduction openings a key-lock coding.
 6. Exchangeable filterinsert as recited in claim 5, wherein: the filter insert has, inaddition to the support arms forming the spring prestresser support,first positioning elements, and wherein, via the first positioningelements and via second positioning elements that work togethertherewith and that are provided on the valve holder in addition to theintroduction openings, the filter insert, during its placement into thefilter, is configured to be guided into a position in thecircumferential direction ready for engagement of its support armsrelative to the introduction openings of the valve holder. 7.Exchangeable filter insert as recited in claim 1, further comprising: ahollow cylindrical filter material body and two end plates oppositelydisposed in relation to the hollow cylindrical filter body; one or eachof the end plates includes a central opening; and an inner grid-shapedsupport body situated at an inner periphery of the filter material bodyconfigured to radially support the filter material body during flow ofliquid being filtered in a radial direction from outside to inside.
 8. Asingle exchangeable filter insert of a filter system, said filter systemcomprising: a filter housing comprising an inlet for liquid to befiltered, an outlet for filtered liquid, a filter bypass valve having avalve seat and a valve body guided so as to be movable in relation tothe valve seat and preloaded in a closing direction, the valve seatbeing situated in the filter so as to be fixed to the filter, the valvebody being guided in the filter so as to be fixed to the filter, aspring configured and arranged to preload the valve body to a desiredvalue in the closing direction and being guided in the filter so as tobe fixed to the filter; and a plurality of exchangeable filter inserttypes, each of said types being configured to preload the valve body toa respectively different desired value; each of said types of theexchangeable filter inserts comprising: a configuration enabling eachexchangeable filter insert to be positioned to separate an unfilteredside and a filtered side of the filter from one another; and a springprestresser support configured, in the state in which each exchangeablefilter insert is positioned in the filter housing, the springprestresser support of each exchangeable filter insert being configuredto support and prestress the spring of the filter bypass valve at itsend oriented away from the valve body; wherein the single exchangeablefilter insert consists of one of said plurality of exchangeable filterinsert types.
 9. The single exchangeable filter insert as recited inclaim 8, wherein: the single exchangeable filter insert, as well as eachof the plurality of exchangeable filter insert types, is configured topreload the valve body to a desired value different from each of allothers of the plurality of exchangeable filter insert types by havingbeen manufactured with a different axial length or a different positionof the spring prestresser support.
 10. A method of using the singleexchangeable filter insert according to claim 9, comprising: selectingsaid single exchangeable filter insert as needed to provide a filter ofthe filter system with a desired preload value of the valve body;installing said single exchangeable filter insert within the filterhousing.
 11. A method of modifying the preload value of the valve bodyaccording to claim 10, comprising: uninstalling said single exchangeablefilter insert from the filter housing; and installing an exchangeablefilter insert from among the plurality of exchangeable filter inserttypes different from a filter type of said single exchangeable filterinsert.
 12. The method of modifying the preload value of the valve bodyaccording to claim 11, wherein: the preload value modification iscompleted by means of the exchange of filter inserts without modifyingother parts of the filter.
 13. Exchangeable filter insert as recited inclaim 1, wherein the spring prestresser support is located on thesupport structure.
 14. Exchangeable filter insert as recited in claim 1,wherein the spring prestresser support of the exchangeable filtercomprises a plurality of radially inward-protruding ribs.